England were tonight facing a potential prop crisis ahead of their RBS Six Nations Championship showdown with title holders France at Twickenham next week.

Tightheads Phil Vickery and Julian White are currently undergoing detailed medical assessment after suffering injuries.

Jason Leonard, meanwhile, who looks set to win his 100th cap against the French, joined Vickery and White in not being able to train during England's two-day squad session, which concluded tonight.

England boss Clive Woodward revealed Leonard was among a group of players who did not train on precautionary grounds, but should be available for selection.

The prospects of Vickery and White making it though, seem far from certain.

Gloucester captain Vickery, whose 29-cap career has been dogged by injury setbacks, is nursing a back problem.

White, available again after serving a ten-week suspension before Christmas, will see a specialist tomorrow. He sustained a knee injury during Bristol Shoguns' Zurich Premiership defeat against Leeds two days ago.

``Phil Vickery is having an MRI scan on his back tomorrow, and we will await the result of that before making any decisions on his availability for the France game,'' said Woodward.

``Julian White had an MRI scan on his left knee today, and will see a specialist in Bristol tomorrow.

``Again, we will wait for these results before making any decisions, and when they have been reviewed by our medial team, then we expect to make a further announcement.''

The front-row situation is compounded by long-term injuries to Trevor Woodman and David Flatman, leaving Woodward with a king-size headache should both Vickery and White also be ruled out.

The likely option would be switching Leonard from loosehead to tighthead and recalling experienced Leicester prop Graham Rowntree, although Northampton's uncapped Robbie Morris is another candidate.

Vickery is battling to be fit for Gloucester's West Country derby against Bath on Saturday, and if he doesn't play, then his England hopes would appear remote.

``I am in pieces with it at the moment,'' he said.

``The back has not been good for a while because of stiffness. But during the team run before the Powergen Cup match with Saracens the weekend before last I stumbled off balance and that was it, game over.

``I have had bangs before but nothing serious. I am having an X-ray today and seeing a specialist tomorrow to make sure it is not a disc problem.

``I am not able to train let alone play - but these things can settle down as quickly as they flare up,'' he added hopefully.

``I have not done anything for nine or 10 days now, though, and it is a worry.''

Lawrence Dallaglio, James Simpson-Daniel, Andy Gomarsall, Mike Tindall, Will Greenwood and Mark Regan also did not train.

``As part of our ongoing partnership with the clubs, they will be monitored by the England and club medical teams. It is expected that they will all be in contention for selection for the France game,'' Woodward added.

``This was our last opportunity to get together before the match against France, and the two-day session was a good one.

``Having the players together at this time has been invaluable, and I would like to thank the clubs again for their continuing support.''