Top secret documents from the Swedish foreign ministry show that government officials have known of the US embassy’s Surveillance Detection Unit (SDU) for years, the Dagens Nyheter (DN) newspaper reports.

Sources within the government offices tell the newspaper that the foreign ministry received information about the programme when Anna Lindh was foreign minister.

Two weeks ago Norwegian media revealed the existence of an SDU programme run out of the US embassy in Oslo.

Within days of the reports from Norway, Swedish justice minister Beatrice Ask confirmed that the US embassy in Stockholm had operated a similar programme since 2000 and that “neither (Swedish security service) Säpo or anyone in the ministry has previously received any information about it”.

Spokespeople for the US embassy in Stockholm and the US State Department in Washington have maintained that the programme was not secret, but was a security measure meant to protect US embassies around the world.

State Department spokesman Philip Crowley traced the origins of the surveillance programme to the 1998 bombings of US embassies in Kenya and Tanzania, arguing that the it had become customary procedure.

“We have acknowledged that we have a programme around the world where we are alert for people who may be surveilling our embassies because we recognize that they are potential targets of terrorism,” he told reporters at a press briefing last week.

Nevertheless, Sweden’s chief prosecutor on security issues, Tomas Lindstrand, launched “a preliminary investigation of illegal intelligence activities” in order to assess whether the US embassy’s programme may have violated Swedish law in its efforts to “protect the US mission in Stockholm and American personnel”.

US embassy spokesperson Ryan Koch said he welcomed the Lindstrand’s decision to open a probe into the programme.

“The embassy is very open about this programme and we’re very willing to cooperate with the prosecutor’s office in any way we can,” he told The Local.

“We understand Swedish concerns and are trying to be as open as we can so we can clear up any misunderstandings.”

Earlier this week, the security services in both Norway and Denmark admitted they knew about the US embassy programmes in their respective countries prior to recent media reports.

The Social Democrats’ current foreign policy spokesperson Urban Ahlin on Friday demanded that the government call a meeting of Sweden’s foreign policy council and explain the contents of the secret documents cited in DN’s report.

“Despite my requests that the opposition be informed about what every agency new regarding the surveillance, the government has instead leaked a document to a morning newspaper in which anonymous sources claim this and that,” Ahlin told TT.

He pointed out that he had repeatedly expressed his disbelief that no Swedish government agency knew about a US embassy programme which had apparently been in place for so many years.

“In the Riksdag’s justice committee Beatrice Ask explained that no Swedish authorities know about this. You’d think that the justice minister should have checked with the foreign ministry before she said that,” said Ahlin.

However, Ahlin had no comment on the fact that the documents ended up at the foreign ministry under a Social Demcrat-led government.

“I don’t know what the documents are about of if there was any reason for those who were responsible to act,” he said.