The British ambassador to Indonesia has been summoned to explain why a separatist group was allowed to set up an office in Oxford.
The Free West Papua Campaign opened its headquarters in the city last month.
British ambassador Mark Canning has met Indonesian foreign minister Marty Natalegawa, who expressed "strong concern" over the situation.
In a statement, the campaign group said Indonesia "can no longer silence the Papuan people".
It added: "Support and awareness of the suffering and injustice in West Papua is growing rapidly all around the world."
Mr Canning said he assured the Mr Natalegawa the new office had "nothing whatsoever to do with the British Government".
Before meeting the ambassador, Mr Natalegawa issued a statement saying the opening of the office was "clearly incompatible and contrary to the friendly relations that have existed between the two countries".
Mr Canning said he told the minister Britain "recognised the sensitivity of this issue for Indonesia" and does not support calls for Papuan independence.
He said Britain also supported Indonesian efforts to "address the problems of Papua and hopes to see it enjoy the same level of peace, stability and prosperity as the other parts of this nation".
The Free West Papua Campaign wants a referendum on independence from Indonesia.
Oxford East MP Andrew Smith, who attended the office opening, has so far been unavailable for comment.