Chris Ashton insists he is committed to Northampton for the rest of the season despite reports of a training ground argument with the Saints' director of rugby, Jim Mallinder, following the England wing's announcement that he was joining Saracens in the summer.

Ashton, who has averaged nearly a try a game in the five seasons he has been at Northampton, is believed to have negotiated a salary of £250,000 a year with the Premiership champions, a hike of around 40% on his wages at Franklin's Gardens.

Ashton was reported to have had rowed with Mallinder this week when he said he was joining Saracens and to have walked out when told he would not be selected to face Munster in the Heineken Cup group match at Milton Keynes on Saturday.

There was speculation that Ashton, who will spend most of the next two months on England duty, would not see out his contract but he denied that. "I have decided to join Saracens next season," he tweeted. "Until then it is all about Saints."

Saracens' reaction to landing the leading try scorer in last season's Six Nations was muted, unlike when they signed the Northampton prop, Soane Tonga'uiha, two years ago, only for the Tongan to later change his mind. "We are obviously especially delighted but, for now, Chris remains a Northampton player," Saracens said in a statement. "Out of respect for Saints, Saracens will not make any further comment at this time."

Ashton has been linked with Saracens since returning from the World Cup, where he was the joint-top try scorer, in October. Earlier last year he indicated he would sit down with Northampton after the tournament to talk over a new contract, but there were no discussions.

Mallinder, who will have to find a new No8 next season after Roger Wilson's decision to return to Ulster, said he had been expecting Ashton to leave, adding: "We have been planning to use that part of the salary cap to strengthen our squad in a number of positions.

"We are disappointed Chris wants to play his rugby elsewhere, but we have several good wings at the club and they will contribute massively to the continued development of the Saints."

Scotland have drafted the Edinburgh fly-half Phil Godman into their Six Nations squad. He covers for the injured Ruaridh Jackson and Steve Shingler, the London Irish pivot whose bid to represent the land of his mother was scuppered by his single appearance for Wales Under-20 on 5 January this year.