The full-back incurred the injury during England's game against Ireland on Sunday.

After seeing specialists this week, and a hand specialist in Manchester on Wednesday, the England medical team confirmed he has torn the ulnar collateral ligament in his right thumb and is expected to be out of action for five weeks.

The Sale Sharks captain will have an operation on Friday in a Manchester hospital.
Robinson said: ''This is very disappointing for me as it means I miss England's last two games in the Six Nations at Twickenham and two games for my club, Sale Sharks. But I'm looking to be back playing very early in April.''

England head coach Andy Robinson commented: I am hugely disappointed for Jason. As England captain he has been an immense figure during the autumn internationals and the Six Nations, leading by example at all times. I look forward to having him back in the England squad.''

England announce their 30-man squad on Thursday to train for their RBS 6 Nations game against Italy at Twickenham on March 12.

Andy Robinson will now have to appoint a third captain this season.

Even before Robinson had been confirmed as Sir Clive Woodward's successor he had named Jonny Wilkinson as the man to lead England to the 2007 World Cup.

But then Wilkinson suffered an arm injury which ruled him out of the autumn internationals before knee ligament damage sidelined him for the RBS 6 Nations.

England then turned to Jason Robinson, the former rugby league international, who has been highly praised by team-mates and coaches alike for the way he has led the side this season.

Now Andy Robinson faces a quandary - and his options are limited.

Wilkinson is not expected to play for England in the remainder of the championship.

Mike Tindall, Richard Hill and Phil Vickery are all out injured and the only player in the current squad with international captaincy experience is Matt Dawson - who is being kept out of the starting XV by Harry Ellis.

Ben Kay, who has returned to form following a post-World Cup slump, is pack leader and would appear to be one of the leading candidates to take over.

Martin Corry, the in-form Leicester number eight, has captaincy experience with Bristol while Steve Thompson is Northampton skipper.