Former cabinet minister in the Tony Blair government Clare Short alleged that intelligence agencies spied on United Nations Secretary General Kofi Annan in the run-up to the Iraq War, Sky News reports.

Blair's office, however, hit back saying 'security always acts within the law'

Short's revelation came hours before Blair is scheduled to be questioned about the collapse of the case against former intelligence officer Katharine Gun.

Short made her claim while being interviewed on BBC Radio 4's Today programme about the implications of the collapse of case.

In response to question whether British spies were on Annan's tail, Short said, "I know, I have seen transcripts of Kofi Annan's conversations."

"Indeed, I have had conversations with Kofi in the run-up to war thinking, 'Oh dear, there will be a transcript of this and people will see what he and I are saying'," she added.

She said, "yes, absolutely" when asked the British intelligence agencies were acting on instructions from higher authorities.

"Absolutely, I read some of the transcripts of the accounts of his conversations," she said when asked if she had seen the transcripts.