STOCKHOLM (AFP) - Swedish police cordoned off two large areas of central Stockholm on Thursday after a man entered the offices of a human rights group with a suspect device.

"The man claims to have an explosive object," police spokesman Sven-Erik Olsson told Aftonbladet TV while local media reported that the man was believed to be wearing a bomb belt.

"The man has expressed his dissatisfaction with parties in the parliament," the police added in a statement, explaining that two main streets in the city centre had been closed off.

The human rights group Civil Rights Defenders is located just four doors away from the offices of the ruling Moderate Party in Stockholm's old town.

Bomb disposal technicians were at the location and police had cordoned off the street from early afternoon as well as another area north of the old town where the Social Democratic Party has its headquarters.

The two normally bustling streets were completely empty apart from emergency services and police who said that they had telephone contact with the man and had engaged in negotiations.

Three dark sedan cars with masked anti-terror forces arrived near the building and a bomb disposal robot was sent down the street, said an AFP reporter at the scene in the late afternoon, as police extended the security cordon and witnesses reported seeing heavily armed police with crowbars and other tools used for forcing entry.