A BBC reporter in North Korea was detained, interrogated for eight hours and eventually expelled over his reporting in the run-up to a rare ruling party congress, the British broadcaster said on Monday.

Foreign reporters invited to cover specific events in North Korea are subjected to very tight restrictions on access and movement.

Numerous journalists have been prevented from returning because their previous coverage was deemed "inaccurate" or "disrespectful" - but detaining and then expelling a reporter while still in the country is extremely rare.

The BBC journalist, Rupert Wingfield-Hayes, was about to board a plane departing from Pyongyang airport with two other BBC staff on Friday when he was stopped and taken into detention, the BBC said.

He was then questioned for around eight hours, apparently over one of his reports which questioned the authenticity of a hospital his team was visiting.

"He was taken to a hotel and interrogated by the security bureau here in Pyongyang before being made to sign a statement and then released" on Saturday morning, said John Sudworth, another BBC reporter covering the congress in the North Korean capital.

Sudworth said the BBC had sought to keep the detention and expulsion order quiet out of concern for the safety of Wingfield-Hayes and two other members of his team, who had refused to leave on Friday after he was detained.

However, an official with the North's National Peace Committee broke the news at a press conference early Monday, when he criticised Wingfield-Hayes for "speaking very ill of the system and the leadership of the country".

"We are never going to allow him back into the country for any reporting," he added.

'Very, very serious'  

The three-person BBC team landed in Beijing from Pyongyang on Monday evening.

"We are very happy to be back in Beijing," the team's producer Maria Byrne tweeted at around 7 pm local time.

Wingfield-Hayes emerged from the terminal 3 arrivals area at Beijing International Airport at around 7:20 pm, and did not stop for the dense pack of reporters and cameras waiting for him.

"We are not making any statement now or interviews. Obviously I am glad to be out. We are going to talk to our bosses now," he said.

During their interrogation, the North Korean authorities had made it clear to Wingfield-Hayes that they saw the content of his reporting as a "very, very serious issue", Sudworth said.

A spokesman said the BBC was "very disappointed" at the treatment of Wingfield-Hayes and his team.

The BBC team had been working in North Korea for several days ahead of the party congress opening on Friday, accompanying a delegation of Nobel prize laureates conducting a research trip.

There are currently around 130 foreign journalists in Pyongyang - all of whom were ostensibly invited to cover what is the first Workers' Party congress to be held for more than 35 years.

However, access to the conclave has been limited.

Reporters were allowed in for the announcement of Kim Jong-Un's new title - chairman of the Worker's Party - but otherwise coverage of the event has been restricted to watching state television and a brief photo opportunity across the street from the venue on Friday.

In the meantime, the journalists have been taken on formal excursions around Pyongyang, including visits to a wire factory, Kim Il-Sung's birthplace and a maternity hospital.

Sudworth said Wingfield-Hayes' expulsion had raised serious concerns among those reporters still in Pyongyang.

"The idea that somebody would be prevented from leaving the country and put under this kind of pressure simply because the North Korean authorities disagree with the content of his reporting... is not just for me, as one of his colleagues, but for other journalists here, of deep concern," he said.