Three brothers and their mother have been remanded in police custody for up to four weeks on suspicion of taking part in the bombing of the United States embassy in Oslo last week, a Norwegian court said in a ruling on Friday.
The US embassy was hit by an explosion on Sunday, and police later said they had apprehended the suspects, accusing them of a "terror bombing" intended to kill or cause significant damage.
The powerful early-morning blast from an improvised explosive device (IED) damaged the entrance to the embassy's consular section but caused no injuries, Norwegian authorities have said.
One of the men has admitted to placing a device, while the three other suspects have denied involvement; their lawyers have said.
US embassy in Norway targeted
The US embassy in Oslo was hit by an explosion early on Sunday, causing minor damage but no injuries, Norwegian police said.
"We've determined that an explosion hit the American embassy," police spokesperson Mikael Dellemyr told public broadcaster NRK, adding that the blast occurred at the entry to the consular section.
No suspects have been identified at present, but police are searching for one or several perpetrators and are cooperating closely with the embassy, said Frode Larsen, head of the Oslo police investigation unit.
"One of our hypotheses is that this is terrorism, but we are also exploring other options," Larsen later told NRK.
It was not immediately clear what caused the blast or who was involved, the Oslo police department said in a separate statement.
"The police are in a dialog with the embassy, and there are no reports of any injured persons," the statement said.