Security forces in Qatar detained two journalists from Norwegian state television for more than 30 hours and deleted footage they had gathered at a migrant labour camp as they tried to report on worker issues ahead of the FIFA 2022 World Cup, authorities said on Wednesday.

Qatar’s government later accused NRK journalists Halvor Ekeland and Lokman Ghorbani of “trespassing on private property and filming without a permit” as the two returned early on Wednesday to Norway following their arrest.

The Norwegian prime minister, Jonas Gahr Stoere, responded by saying their arrest was “unacceptable.”

“A free press is crucial in a functioning democracy,” Gahr Stoere wrote on Twitter.

“This also shows the importance of this year’s awarding of the Nobel Peace Prize (to journalists). I am very happy that Halvor Ekeland and Lokman Ghorbani have now been released.”

Norwegian news agency NTB later reported that the Qatari ambassador to the country was summoned to Oslo’s foreign ministry over the matter.

The arrests, a year ahead of the World Cup, show the ongoing sensitivity felt by the autocratic government of Qatar, a small, energy-rich nation on the Arabian Peninsula.

Other journalists have faced similar problems and detentions while reporting in Qatar as well ahead of the World Cup.

Ekeland, a sports journalist, and Ghorbani, a photographer, had been in Qatar as the country marked one year to go before the World Cup.

The pair were reportedly detained after reporting on the condition of migrant labourers during a live report.

The journalists told NRK that they were not allowed to leave with their equipment. The Norwegian union of journalists and the country’s football federation both criticised the journalists’ arrest.

“It is pretty good to be back on Norwegian soil,” Ekeland told reporters upon arrival at the Oslo airport. “It has been some challenging days but we knew lots of people were working for us, so that was good.”

“We were held for 32 hours,” he said.

In a statement to NRK, foreign minister Anniken Huitfeldt said “they were arrested while performing their duties as journalists.”

“Freedom of expression is the mainstay of a functioning democracy, and also fundamental to be able to fulfil other human rights,” she said.

Qatar’s government said in a statement that the two had been arrested after receiving a complaint from an unidentified private property owner in the country’s industrial area, which is home to labour camps.

It said that Ekeland had applied for a film permit, but authorities had not granted it before he went to the site.

Qatar, like other Gulf Arab states where speech is strictly governed, require journalists to have permissions to operate and to film.

“As in almost every country, trespassing is against Qatari law, which the crew members were fully aware of before entering the property,” the government said.

It acknowledged that “the footage they captured while trespassing was deleted by the authorities in accordance with Qatari law”.

Asked about the Qatar government’s comments about the journalists, NRK declined to immediately comment, saying “our main concern now is their wellbeing”.

Qatar, which sticks out like a thumb into the Persian Gulf, is home to the forward headquarters of the US military’s Central Command.

It has faced increased scrutiny over the treatment of migrant labour in the country since winning the right to host the forthcoming tournament.