The Guardian on Tuesday said Craig Murray had been prevented from returning to the Uzbek capital Tashkent while the home office reviewed his security clearance.
The 43-year-old diplomat has worked in Uzbekistan since August 2002 but received a phone call just hours before flying back to the central Asian country.
The foreign office told Murray his return had been postponed until the high-level vetting that senior diplomats require for access to sensitive documents was reviewed, the newspaper said.
One of Britain's youngest envoys, Murray attracted international attention in 2002 when in a speech to local officials and fellow diplomats he declared Uzbekistan was not a functioning democracy.
He highlighted the routine use of torture in prisons. In one case two men were allegedly boiled to death.
His 2002 speech, which had been cleared by the foreign office, was taken up by United Nations Secretary-General Kofi Annan when he met President Islam Karimov, in power since 1990.
Murray has been bitterly critical of what he sees as the double standards of the US which has given tens of millions of dollars to Tashkent as an ally in its "war against terror".