Describing such behaviour as "disgusting", Blix told Britain's Guardian newspaper in an interview: "It feels like an intrusion into your integrity in a situation when you are actually on the same side."
His allegation came on top of a diplomatic row sparked this week when former British minister Clare Short said Britain bugged UN Secretary General Kofi Annan's office as London and Washington tried but failed to win UN backing to invade Iraq.
Blix said his suspicions were raised when he had trouble with a telephone connection at home.
"It might have been something trivial or it might have been something installed somewhere, I don't know," he said.
The Swede said he asked UN counter-surveillance teams to check his office and home for listening devices.
"If you had something sensitive to talk about you would go out into the restaurant or out into the streets," said Blix.
He said US State Department envoy John Wolf visited him two weeks before the Iraq war with pictures of an Iraqi drone and a cluster bomb the former inspector believed could have been secured only from within the UN weapons office.
"He should not have had them. I asked him how he got them and he would not tell me," Blix said.
"It could have been some staff belonging to us that handed them to the Americans ... It could also be that they managed to break into the secure fax and got it that way," he said.
Short claims Britain has bugged
Koffi Annan's offices in London
Short, in government before and during the Iraq war, said on Thursday she had seen transcripts of what she said were bugged accounts of Annan's conversations. She resigned after the war.
In an interview on Saturday with The Independent newspaper, Short said it was likely Blair would not have known that the transcripts were circulated around government.
"I'm afraid that there is no question that such transcripts were regularly circulated," Short said.
"It is likely that the prime minister was unaware of this," she said.
"He's not a man for detail but he is in a position to stop the practice."
Short also rubbished suggestions her disclosure Britain had been listening in to Annan was a threat to Britain's national security or intelligence services.
"It feels like an intrusion into your integrity in a situation when you are actually on the same side"
Former chief UN weapons inspector
British Prime Minister Tony Blair accused her of being irresponsible and of undermining intelligence services at a time when Britain faced a threat of attack. Blair said British security services acted within domestic and international law.
But UN spokesman Fred Eckhard said Annan would seek a fuller explanation from Britain on the allegations, saying any attempt to eavesdrop on the secretary general was illegal and should stop, as it would violate three international treaties.
Blair warned critics like Short that unless they buried differences they risked ousting his Labour Party from power as it prepared to fight a general election expected in 2005.
"From the first day I entered my office they told me: beware, your office is bugged, your residence is bugged"
Butros Butros-Ghali ,
Former UN Secretary-General
Former UN Secretary-General Butros Butros-Ghali and another former chief UN weapons inspector, Richard Butler, said on Friday they believed they had been spied on.
"From the first day I entered my office they told me: beware, your office is bugged, your residence is bugged," Butros-Ghali told the BBC.
"It is a tradition that member states that have the technical capacity to bug will do it without hesitation," he said.