Reporting from London —Three men suspected of preparing to mount a terrorist attack were arrested in Norway and Germany on Thursday in what authorities said was an Al Qaeda plot with strands in the United States and Britain.
After a lengthy period of surveillance, the men were taken into custody by police, who feared that information about the investigation might surface in the media.
Two of the suspects were arrested in Norway and one in Germany. Their names were not released, but police in Oslo described all three as legal residents of Norway, one a citizen and the others holders of permanent residency cards.
"We believe this group has had links to people abroad who can be linked to Al Qaeda, and to people who are involved in investigations in other countries," including Britain and the U.S., Janne Kristiansen, the head of Norway's Police Security Service, told reporters.
She declined to provide details about the alleged plot or its intended target because the investigation was ongoing. But police said the public had never been in imminent danger
"The people of Norway have no reason to walk around and feel afraid," Kristiansen said. "We are not in any acute danger of terrorism."
News reports said the men were preparing an assault with bombs made from peroxide, similar to a disrupted plan last year to attack the subway system in New York.
Two U.S. citizens, originally from Afghanistan, have pleaded guilty in connection with that plot, which the U.S. says was masterminded by Salah al-Somali, an Al Qaeda leader who was killed in an airstrike in Pakistan last December. Al-Somali was in charge of Al Qaeda attacks worldwide.
An indictment unsealed in New York on Wednesday linked the thwarted attack on the subway with a similar plot directed at northern England.
Siv Alsen, a spokeswoman for Norway's Police Security Service, would neither confirm nor deny whether the plot revealed in Oslo on Thursday was connected with the two in New York and northern England.
The investigation into the three men arrested Thursday had been underway "quite a while," Alsen said. But the arrests were brought forward because American media had gotten wind of it last week, and police were worried that they would publish the information soon.
Kristiansen said the arrests were carried out with the assistance of authorities abroad, but she did not name which countries.
The suspects included a 39-year-old man of Uighur descent who had arrived in Norway as a refugee in the late 1990s and obtained Norwegian citizenship in 2007, and an Uzbek, 31, who had been granted permanent residency in Norway. Both were arrested in Oslo.
The third suspect, described as a 37-year-old Iraqi Kurdish man, was arrested in Germany in the Frankfurt area, authorities said. He too held a permanent residency permit in Norway.
The Scandinavian country was singled out in 2003 as an Al Qaeda target by the terrorist network's No. 2 leader, Ayman Zawahiri. Exactly why is unclear. Some observers say it's because of the country's involvement in the Oslo accords between Israel and the Palestinians, which extremists vilified; others say that Norway's involvement in the war in Afghanistan could now be a factor.
Prime Minister Jens Stoltenberg on Thursday defended the presence of his nation's troops in Afghanistan.
"Norway is in Afghanistan to combat terror," he said. "We are there because we want to avoid Afghanistan becoming a haven for international terrorism. We went in with our NATO allies."
He said legitimate opposition to Norwegian policies could not include violence.
"We value freedom of speech highly and must tolerate many expressions of it. But we have no tolerance for the use of terror and violence to achieve goals," Stoltenberg said.
Meanwhile, in a London court, three men were convicted of conspiracy to murder in connection with a 2006 plot to bring down several transatlantic passenger jets midflight.
It was the third time the men had been tried. Last September, a jury acquitted them of knowingly participating in a plot to attack airliners, but prosecutors decided to retry them on a general charge of conspiracy to murder, without reference to the actual targets.
As evidence of their deadly intent, prosecutors showed "martyrdom videos" that the men had made. The three — Arafat Khan, Ibrahim Savant and Waheed Zaman — now face life in prison.
The planned attack caused major disruption to air travel and ushered in restrictions on liquids being brought on board planes by passengers.
The plot's ringleader was convicted last September, as were two other men.