Lawyers acting for Sir William Stubbs, the sacked former head of the government's exams watchdog, are seeking disclosure of key government documents relating to his dismissal, including any directions from 10 Downing Street.

Sir William claims he was humiliated when he was sacked by the former Education Secretary, Estelle Morris, at the height of the row over A-level grades.

He is demanding a public apology and has pledged to sue for wrongful dismissal if the government does not oblige.

A letter issued late last night by Sir William's solicitors - Bernard Clarke and Co - to Education Secretary Charles Clarke said they would require disclosure of "all relevant documents".

14 days to settle

"This would include internal minutes, inter-departmental memorandums, the documents or other written evidence on which the secretary of state relied, in particular, any directions, advice or other communications from Number 10 Downing Street," the letter said.

The letter, dated 1 November, gives Mr Clarke 14 days to enter into negotiations to settle the claim, before proceedings begin.

As chief executive of the Qualifications and Curriculum Authority (QCA), Sir William had been accused of pressurising the exam boards to keep A-level grades at a similar level to last year.

He says his reputation has been ruined, which is why he plans to sue the government for wrongful dismissal unless he receives a public apology.