Defence Secretary Liam Fox has postponed a visit to Sri Lanka, following reported Foreign Office concerns about the trip.
A spokesman said the postponement was due to "an extension to his scheduled official visit to the Gulf" and it would go ahead next year.
The Guardian reported that Foreign Secretary William Hague was annoyed about the trip.
Sri Lanka denies war crimes during its defeat of the Tamil Tigers last year.
Both the Tamil Tigers and Sri Lanka's government have been accused by human rights groups of committing crimes against humanity during the last year of their 26-year conflict.
Earlier this month demonstrators tried to storm the British high commission in Sri Lanka's capital Colombo, after a speech to the Oxford Union by Sri Lankan President Mahinda Rajapaksa was cancelled, following Tamil protests in the UK.
Dr Fox has had an interest in Sri Lanka since his efforts to broker a ceasefire in the conflict when he was a junior Foreign Office minister in 1996. He met President Rajapaksa during his UK visit.
The Guardian reported that Dr Fox had accepted an invitation to deliver the Lakshman Kadirgamar memorial lecture, made by the widow of the former foreign minister Mr Kadirgamar, who was shot dead in 2005.
The paper reported Foreign Office sources as having said Foreign Secretary William Hague was "appalled" by the decision.
Questioned about Dr Fox's trip earlier, the prime minister's spokesman stressed it was a "private visit", not a government one, and Dr Fox had "a long-term private interest in Sri Lanka".
Later it was announced the trip would not go ahead this weekend.
A spokesman said: "Dr Fox has postponed his private visit to Sri Lanka due to an extension to his scheduled official visit to the Gulf.
"He intends to carry out an official visit to Sri Lanka next year during which he proposes to fulfil the speaking engagement that he had planned."
For Labour, Yvette Cooper said it was an example of "chaotic diplomacy" and raised questions about Dr Fox's judgement.
She said: "William Hague must be spitting mad. This is a sensitive area of foreign policy. Who is in charge of policy on Sri Lanka, the foreign secretary or the defence secretary?"