The BBC said it was “deeply concerned” about the wellbeing of one its journalists who has been unable to leave Vietnam for several months.
The Vietnamese national travelled to the country to visit family and renew their passport, but the document and their ID card have been withheld and they have been subjected to “multiple days of questioning”, the corporation said in a statement.
The BBC is urging Vietnamese authorities to allow the journalist to leave immediately and return to work by providing the renewed passport.
It comes as general secretary of the Communist Party of Vietnam, To Lam, arrived in the UK on Tuesday, for a visit during which he is expected to meet Sir Keir Starmer.
A Foreign Office spokesperson said the UK’s “position and track record defending media freedom is clear”.
They added: “We remain concerned by reported harassment of NGOs, journalists, and rights activists and communities in Vietnam and continue to raise these concerns directly with our Vietnamese counterpart.”
Vietnam is a one-party Communist state and has been one of south-east Asia’s fastest-growing economies.
But alongside its economic growth, the country has high levels of political censorship and a poor record on human rights.
The Communist Party has a strong grip on the media in Vietnam.
Media outlets and journalists risk sanctions and arrest for broaching sensitive topics and for criticising the government, while online content deemed to threaten Communist rule is blocked.