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This is the second extension of the contract between the WRU and the New Zealander who was originally appointed as Head Coach of Wales in 2007.
That initial contract covering 2007 until 2011 was extended in 2010 until after the 2015 Rugby World Cup. Today's further renewal will ensure Gatland will be the first coach to take Wales to three World Cup competitions.
The announcement is being made as Warren Gatland is celebrating his success in receiving a clutch of major accolades about his world class prowess as a Head Coach.
On Sunday he was made the BBC Sports Personality Coach of the Year just a week after being named the Wales Sport Awards Coach of the Year while days before that he was named UK Coach of the Year at the Sports Coach UK national Awards.
Warren Gatland will now continue to coach the senior Wales squad for the next six years working alongside the WRU Performance and Development teams to ensure a robust player succession plan continues to identify and nurture the international stars of the future.
The announcement has been timed to ensure the Wales coach can focus completely on preparing his squads for the intense international fixture schedule which lies ahead of RWC 2015 and the planning through to 2019.
It also ensures long term continuity at the highest level of the game in Wales to build on Warren Gatland's six years' experience at the helm of the Welsh international game.
WRU Group Chief Executive, Roger Lewis, declared: "I am pleased and honoured to be able to announce that Warren Gatland will remain Head Coach of Wales until after the Rugby World Cup in 2019.
"He has undoubtedly proved that he has the rugby expertise, the passion and the commitment to prepare and inspire our teams to play with the utmost skill and pride for the jersey.
"We now have a meticulous and professional coaching structure in place which Warren must take credit for creating.
"By signing him for a further four years we have ensured that the systems now in place will continue to develop for the future of the international game in Wales.
"It is so important that we achieve continuity at the highest level which is why we have negotiated our Wales international touring fixture schedule right through until 2019.
"The contract we have negotiated contains a significant element which is based on success and we are all working towards the same goal.
"The continuity of excellence is a supremely important factor in the preparation and development of elite, international sports teams in this day and age.
"Of course we considered all the scenarios available, but it became increasingly and abundantly clear that the best option for Wales is Warren Gatland.
"The process which led to this moment began in earnest more than a year ago and it has taken an incredible amount of hard work and negotiation to make sure we got this right for Wales and for Warren.
"We operate in an extremely hard nosed environment and there was never any doubt that we had to achieve a renegotiation which was workable, meaningful and ambitious in terms of our expectations.
"I have great respect for Warren and I know how he lives and breathes rugby and is totally devoted to achieving success for a nation he now calls home from home.
"He makes a lot of sacrifices to ensure he knows everything there is to know about the talent available to him and the other selectors and we can rest assured that the future of the Welsh team will now remain in safe hands.
"In recent years we have created one of the best elite training facilities in the world at the WRU National Centre of Excellence with some of the finest strength, conditioning and medical experts in the game.
"We will never stop developing and improving our systems and structures and I know Warren will continue to play a central part in that process over the years ahead.
"My respect for Warren's ability as a coach is unquestioned and over the years of getting to know him I have come to look upon him as a genuine and honourable man who I am proud to count as a friend."
He has put in place a coaching and backroom structure which is seen as a template for the future and his continued control of its development is a massive bonus for Wales.
The Wales team is now renowned worldwide for its compelling and engaging rugby with all opponents fully aware that Wales pose a potent threat in any game.
During the RBS 6 Nations tournament Warren Gatland will become the longest serving coach of Wales. His first new challenge after this announcement will be the RBS 6 Nations tournament which kicks off against Italy at the Millennium Stadium on the first of February 2014.
Warren Gatland said: "I am proud and delighted to have been chosen by the Welsh Rugby Union to take charge of Wales teams for the next two Rugby World Cup tournaments.
"I have chosen to stay in Wales because of my confidence in the players we have, the coaching structures we have developed and the succession plan of talent we now constantly update.
"I know the other major rugby nations take us seriously as opponents who can play excellent rugby and that inspires me to take this group of players even further.
"There is an incredible amount of hard work ahead but, with the backing of the Welsh Rugby Union, the national squad now has the means to deliver what the Welsh public want.
"We have strong support systems, the international player pathway structure and the WRU National Centre of Excellence is a fantastic facility.
"Our best players now get developed within a totally professional structure and the backroom team we have in place boasts some of the best people around in their areas of expertise.
"I want to personally thank the WRU and the Welsh rugby public for the fantastic support the national squad enjoys and I aim to return the compliment by devoting all my professional energy to the success of our national team in the years ahead.
"I am looking forward to the challenge and I am extremely proud of the honour I have in taking Wales into the next two Rugby World Cups."
Lewis and Gatland furthered their negotiations for a contract extension while they were both in Australia for the British and Irish Lions tour last summer and today the contract extension was unanimously agreed by the full board of the WRU.
WRU Chairman, David Pickering, added: "Throughout a formidable coaching career Warren Gatland has achieved the stature which we want and expect every coach of Wales to possess.
"He has made a huge and positive difference to the Wales team throughout his tenure so far and we know he will endeavour to build on that improvement in the years ahead.
"I know Warren as a clear and concise student of the game who constantly seeks to be innovative and forward looking in his approach.
"He operates in one of the toughest sporting environment and has the strength of will to accept and relish the challenge to meet the high standards the Welsh rugby public demands.
"Welsh rugby is fit for purpose both on and off the field to meet the challenges which lie ahead and I am delighted we have been able to secure the services of Warren Gatland to help us achieve our ambitions."