England and Wasps scrum-half Dan Robson faces an indeterminate spell on the sidelines after developing blood clots – potentially jeopardising his World Cup hopes.

Robson earned his second England cap last weekend, when he came off the bench to score his first international try in the 57-14 thrashing of Italy in the Guinness Six Nations.

The 27-year-old would have been expected to retain his place among the substitutes for Saturday’s closing Six Nations match against Scotland at Twickenham but was ruled out in midweek through illness.

Wasps have now confirmed why Robson’s Championship is over as they said in a brief statement: “Dan Robson suffered blood clots which arose spontaneously earlier this week and (he) is being evaluated and treated by specialists at the moment.

“At this stage it is too early to give a return-to-play date.”

Robson was replaced in England’s squad by Saracens number nine Ben Spencer, who will provide half-back cover for Ben Youngs.

Robson admitted his disappointment following the diagnosis but said he was determined to return to action as soon as possible.

A statement published on his Twitter account read: “Obviously pretty devastated by my recent news but I know I am in the best hands to get back to full health and back on the pitch as soon as I can.

“Appreciate all the support from everyone and a special shout out to all the medical staff that have aided me especially in locating the issue and acting so promptly.”