Farzad Farhangian is the third diplomat in Europe to defect from Iran this year in protest at the government’s crackdown on opposition groups.
His defection follows that of a senior official at Iran’s embassy in Finland, who said on Monday he was seeking asylum there.
Norway granted asylum to another diplomat in February.
There has been no reaction from Iranian officials on Mr Farhangian’s asylum claim, but the previous two defections have been met with statements that the diplomats’ postings had come to an end.
Speaking in Oslo, Norway, Mr Farhangian said he wanted to “take a stand in support of the Iranian people and the [opposition] movement,” Associated Press reported.
A Norwegian-Iranian support group earlier said Mr Farhangian was “seeking asylum from Norwegian authorities because his life was in danger in Brussels”.
Associates of Mr Farhangian said he left the Iranian embassy in Brussels, Belgium, on Friday to fly to Oslo with his family.
The diplomat who defected in Finland on Monday, Hossein Alizadeh, said he had resigned his position in protest over the government’s controversial handling of the disputed June 2009 elections and the subsequent crackdown on opposition protests.
“I describe myself as a soldier for my country, for my nation, not for my regime. Actually this is a regime I don’t belong to at all,” he told the BBC.
President Mahmoud Ahmadinejad was re-elected last year in an election that opposition leaders claim was fraudulent.
Mass protests against the official result were violently dispersed and many demonstrators arrested. – BBC