Sir Malcolm Rifkind is stepping down as chairman of Parliament's Intelligence and Security Committee after criticism over "cash-for-access" claims.The former foreign secretary is also standing down as a Conservative MP.Sir Malcolm said he may have made "errors of judgement" after being secretly recorded apparently offering his services to a private firm for cash, but denied any wrongdoing.He said he did not want the committee's work to be "distracted or affected".Another former foreign secretary, Labour's Jack Straw, also featured in the undercover investigation by the Daily Telegraph and Channel 4's Dispatches.Both MPs have referred themselves to Parliament's standards watchdog and both deny breaching House of Commons rules.'Lack of support'Sir Malcolm, the Conservative MP for Kensington, had previously said he would not stand down as security committee chairman, unless his colleagues wanted him to.BBC assistant political editor Norman Smith said he would have "picked up on the murmurings" about his ability to carry on as chairman and been "acutely aware of the lack of support" from Downing Street.In a statement issued on Tuesday morning, he said while he would remain a member of the committee, he would step down from the chairmanship.The committee is due to publish a report next month looking at surveillance by the intelligence agencies, and Sir Malcolm said he had decided "it is better that this important work should be presided over by a new chairman".