A senior official from Channel 4 has been expelled from Sri Lanka, says the country's government.
Stuart Cosgrove and his wife Shirani Sabaratnam went on a "blacklist", after Channel 4 News said the country's armed forces may have committed war crimes.
Mr Cosgrove's wife was refused a visa and turned back from the airport.
In London more than 500 Tamil protesters jeered the Sri Lankan president, as he arrived at a Jubilee lunch for commonwealth leaders.
The protesters outside Marlborough House on Pall Mall accuse the country's president Mahinda Rajapakse of war crimes.
The Sri Lankan government said Mr Cosgrove - Channel 4's head of diversity - was forced to leave the country shortly after he arrived.
The official in charge of immigration told the BBC's Charles Haviland Mr Cosgrove's expulsion "was not a deportation", but he had simply been "instructed to leave".
He said Mr Cosgrove and his wife, who is of Sri Lankan Tamil origin, were on a watchlist of people not wanted in Sri Lanka.
When asked why they had been blacklisted, the immigration official said: "Because they are from Channel 4, which without reason has harmed Sri Lanka's reputation."
Channel 4 News angered the Sri Lankan government with two documentaries alleging, with video, that the country's armed forces may have committed war crimes.
The programme-makers say the Sinhalese-dominated army used extreme violence against Tamil civilians and prisoners-of-war in 2009.
Channel 4 has strongly defended its journalism, and a spokeswoman said Mr Cosgrove had no editorial role in the Channel 4 film, "Sri Lanka's Killing Fields".
She added Ms Sabaratnam had never worked for the channel and was employed by the digital lifestyle channel, UKTV.
'Peaceful, yet determined'
Meanwhile, the Sri Lankan President Mahinda Rajapakse has cancelled a planned speech in London over fears it may trigger more protests.
More than 500 human rights and Tamil protesters gathered in central London on Wednesday to march along the Strand and Pall Mall before gathering outside Malborough House.
The president's arrival was jeered by the crowd, who shouted "war criminal, we want justice".
The protest was "peaceful, yet determined", said the BBC's world newsgathering producer Jonny Hallam.
He said the protesters then moved to outside the hotel where Mr Rajapakse is staying, where they plan to stay until Wednesday evening.
More than 25 years of civil war between the majority Sinhalese population and the minority Tamil ethnic group officially ended three years ago when government forces seized the last area controlled by Tamil Tiger rebels.
A United Nations report published last year said both sides in the conflict committed war crimes against civilians.
But the Sri Lankan government rejected the report, describing it as biased.