Swedish and Norwegian security police arrested six people Thursday suspected of preparing terrorist acts and financing terror organizations.

Three people were arrested in Oslo and another three in Stockholm in what Sweden's SAPO security police said were coordinated raids.

"Three Swedish citizens have been arrested in the Stockholm area on suspicion of preparation of terror acts and financing of terror organizations," SAPO spokesman Jakob Larsson said.

Norway's police intelligence agency PST said minutes earlier that it had arrested three people in separate locations in Oslo on suspicion of financing terror.

One or more of those suspects would face a detention hearing in court, PST said, adding it would not release any other details before the hearing.

It was not immediately clear whether the suspects arrested in Oslo and Stockholm were linked.

In its annual report earlier this month, PST said violence by Islamic extremists will pose a significant challenge to Norwegian security in coming years, partly because of the Nordic nation's participation in NATO-led peacekeeping operations in Afghanistan.

Norway closed its embassy in Kabul, Afghanistan, on Feb. 10 after being alerted to a terrorism plot. Foreign Ministry spokeswoman Kristin Melsom said the embassy reopened Wednesday.

The threat followed a Jan. 15 attack by militants on a Kabul hotel in which a reporter for the Oslo newspaper Dagbladet was killed. Norwegian Foreign Minister Jonas Gahr Stoere was also there, but later said he did not think he was the target.

In Sweden, Larsson declined to reveal details on the arrests, but said they were not related to Swedish artist Lars Vilks, who was placed under police protection last year after receiving death threats from al-Qaida in Iraq.

Vilks had made a cartoon of the Prophet Muhammad that angered Muslims when it was published in a Swedish newspaper.