England wing Sackey, also at Toulon, and French centre Bastareaud (Stade Francais) join a back line featuring three former Rugby World Cup winners in South Africans Ruan Pienaar (Ulster), Francois Steyn (Racing Club) and England and Biarritz full-back Ian Balshaw.
The quartet of Italian Talisman Sergio Parisse, Basteraud, Pienaar and Hayes will all be making their Barbarians debuts, adding their names to an illustrious list of more than 3,760 players who have worn the famous black and white hoops since 1890.
"Every summer we take the opportunity to bring a wide range of players together from the top echelons of the rugby world and invariably there are a number of quality internationals who are privileged to make their Barbarians debuts," said Barbarians team manager Alan Evans.
"The names of Parisse, Bastareaud and Pienaar will sit comfortably in the great history of Barbarians rugby and it is also with great pride that we have the opportunity to reward John Hayes for the great service he has done to Irish rugby by handing him his Baa-baas debut."
Wales skills coach Neil Jenkins, a Barbarian on six occasions himself, has backed the newcomers to revel in the unique philosophy of Baa-baas rugby.
Jenkins played for the Barbarians agianst Ireland in Dublin, Scotland at Murrayfield, South Africa in Cardiff, Leicester Tigers twice - at Leicester and Twickenham - and Newport at Rodney Parade.
He was on the losing side on two occasions, against the Springboks and in the Tigers match at Welford Rd, but it is also worth noting that the Barbarians have beaten all three of the top Southern Hemisphere nations, a feat that some of the Home Unions have yet to achieve.
"When you play for the Barbarians there is a different atmosphere, you prepare in a different way," said Jenkins.
"The build up is more relaxed, they'll have a couple of training sessions but they'll get to know each other in that week leading up to the game and won't do the same physical work the international side will do.
"It's more reminiscent of how you might prepare for a match in your younger days at school or for your local club, you are relying on your own skill and the talents of those around you on a match-day to win the game.
"But the difference is that the talents of those around you are the honed talents of some of the best international players in world rugby.
"The Barbarians will be going out there to enjoy themselves and entertain the crowd, but they are all winners so enjoying themselves will mean they will want to win.
"The Baa-baas have won all over the world playing like this, sometimes when you can relax in this way it brings out the best in rugby players and the games can be quite something to watch."
The Barbarians have now named nine of their squad for their tour this summer, which also sees them face England at Twickenham before the English head for Cardiff in August.
Australian legend George Smith, who is set to partner Parisse in the back row, completes the list.
"There is no doubt that this Wales team will have to be right at the top of their game to win this match, with some of the top names in world rugby already on the Baa-baas team sheet, and nothing less than a win is going to be good enough for us either," added Jenkins.
"There can be similarities with the Barbarians and some of the South Sea Island teams, they can throw off the shackles sometimes and come at you and we will have to be ready for that with both Samoa and Fiji in our World Cup group,"
Wales have lined up against the famous black and white hoops on six occasions losing four times and winning just twice - when Jenkins was capped in 1996 and in the last outing in 2004.
The other capped international against the Barbarians was Wales' first in 1990, which the Baa-baas won 31-24.
Tickets remaining for the summer RWC warm-up fixtures against the Barbarians and England at the Millennium Stadium are priced at £40 and £30 for adults, £100 for a family ticket (2 adults 2 children) for the Baa Baas game and £110 family ticket for the England match, with a new category introduced this season of £15 for the under 18s enclosure.
The final game on homes soil against Argentina is priced at £30 and £20 for adults, £70 for a family of four and £15 for the under 18s enclosure.
Tickets can be purchased online at www.wru.co.uk/tickets or by calling the ticket hotline 08442 777 888.
Sat 4 June 2011 - Wales v Barbarians, Millennium Stadium (KO tba)
Sat 13 Aug 2011 - Wales v England, Millennium Stadium (KO 2.30pm)
Sat 20 Aug 2011 - Wales v Argentina, Millennium Stadium (KO tba)
Wales v Barbarians: Full record
Wales 24-31 Barbarians, Cardiff Arms Park, 06-10-90 L CAPPED
Wales 31-10 Barbarians, Cardiff Arms Park, 24-08-96 W CAPPED
Wales 38-40 Barbarians, Millennium Stadium, Cardiff, 20-05-01 L
Wales 25-40 Barbarians, Millennium Stadium, Cardiff, 29-05-02 L
Wales 35-48 Barbarians, Millennium Stadium, Cardiff, 31-05-03 L
Wales 42-0 Barbarians, Millennium Stadium, Cardiff, 26-05-04 W