Dissident Chinese artist Ai Weiwei said on Thursday that Britain had denied his application for a six-month visa in favour of one with a shorter duration, telling him that he had not declared a previous “criminal conviction”.

The denial of a longer visa comes three months before President Xi Jinping visits Britain and could fuel criticism of prime minister David Cameron’s government, which has been accused of putting trade before human rights in dealing with China.

Ai has never been charged or convicted of a crime.

In 2011, the Chinese government said Ai remained under investigation on suspicion of economic crimes after he was released on bail. Ai said previously that he had not received a formal notice to explain “suspected economic crimes”.

Authorities in Beijing returned Ai’s passport last week, more than four years after it was confiscated following his 81-day secret detention.

In a letter issued by the UK Visas and Immigration Department that Ai posted on Instagram, the department said Ai had not declared that he had “previously received a criminal conviction in China”.

Reuters was unable to immediately verify the authenticity of the letter.

In a statement provided by the British embassy in Beijing, a Home Office spokesperson said: “All applications are considered on their individual merits and in line with the relevant legislation. Mr Ai has been granted a visa for the full duration of his requested dates of travel.”

Ai said he had been given a visa to travel to Britain from September 9th-29th but added that he “may not be able to attend the exhibition installation and opening” of a retrospective of his work at London’s Royal Academy of Arts that month. The exhibition is due to open on September 19th, according to the Royal Academy’s website.

Ai could not be reached for comment. He told Reuters earlier that he was headed on an afternoon flight to Munich in Germany.

“This decision is a denial of Ai Weiwei’s rights as an ordinary citizen,” Ai said on Instagram.

China’s foreign ministry did not respond to a request for comment.

The denial of Ai’s six-month visa has been criticised by human rights activists and could turn into a public-relations nightmare for Britain if activists end up protesting over the issue.

In 2012, China took offence at Mr Cameron holding a meeting with exiled Tibetan spiritual leader the Dalai Lama, whom Beijing deems a separatist. A senior source in his office told Reuters in 2013 that Mr Cameron had no plans to meet the Dalai Lama again.

Reuters