Andy Williams picked up a back injury in training

Dragons scrum half Andy Williams has become the latest player to pul out of Wales' summer tour to South Africa.

Williams, 27, suffered a recurrence of a back problem he picked up in training and coach Warren Gatland does not plan to replace him.

That leaves uncapped Warren Fury of London Irish as back up to Gloucester's Gareth Cooper, although Shane Williams could also be used at scrum-half.

Gatland is already without a number of key players for the tour.

Grand Slam heroes Martyn Williams, Lee Byrne, Gavin Henson, Mike Phillips, Dwayne Peel and Alix Popham are all out.

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And more recently, hooker Huw Bennett added to Gatland's injury crisis by withdrawing after damaging ankle ligaments in Shane Williams' testimonial game last Saturday.

Bennett's Ospreys team-mate Richard Hibbard, 24, could be called up.

Wales leave for South Africa on 29 May and play the Springboks in two Tests - at Bloemfontein's Vodacom Park on 7 June, followed by Pretoria's Loftus Versed the following Saturday.

Wales squad for their summer tour South Africa:

Backs: Morgan Stoddart, Andrew Bishop, Jamie Roberts, Shane Williams, Tom James, Mark Jones, Sonny Parker, Tom Shanklin, Stephen Jones, James Hook, Warren Fury, Gareth Cooper.

Forwards: Ryan Jones (Captain), Dafydd Jones, Jonathan Thomas, Gareth Delve, Bradley Davies, Ian Evans, Alun-Wyn Jones, Ian Gough, Duncan Jones, Gethin Jenkins, Rhys Thomas, Adam Jones, Matthew Rees.