The government's official sleaze watchdog has criticised Tony Blair for failing to implement a recommendation to establish clearer mechanisms for investigating allegations against ministers.

The Committee on Standards in Public Life made its comments amid a continuing row over claims that the home secretary abused his position to help the nanny of a former lover.

David Blunkett has announced an independent review into the claims, to be conducted by a senior official appointed by Home Office permanent secretary John Gieve.

But Sir Alistair Graham, who now chairs the standards committee, said the government should establish independent mechanisms for investigating such allegations.

In a brief statement issued on Monday, the watchdog said it had no mandate to investigate allegations against individuals, and would not comment on the latest allegations.

"The committee has however been interested for some time about the way in which allegations that ministers' have conflicts of interest between their public and private life are investigated," said a statement.

A previous report had called on the government to adopt a revised approach to the investigation of allegations against ministers.

"These recommendations, which included the appointment of an independent adviser on ministerial interests to advise ministers and the nomination after consultation with opposition parties of individuals of senior standing to conduct investigations, were designed specifically to address the type of investigation which is currently the subject of considerable speculation," added the statement.

"This would have removed the risk of permanent secretaries being drawn into political controversy and of the process of investigation itself becoming contentious."

Sir Alistair Graham said the committee "was disappointed that the current government did not take the opportunity to put this mechanism in place, particularly as it provides speedy and independent investigation of allegations against ministers".

"Current events demonstrate the continuing practical relevance of adopting these recommendations," he added.