Finnish PM unharmed after attack

Police in Finland swooped on a knife-wielding man who tried to attack the PM on the campaign trail. (AAP)

Police in Finland swooped on a knife-wielding man who tried to attack the PM on the campaign trail. (AAP)

Police in Finland have swooped on a knife-wielding man who tried to attack the prime minister on the campaign trail.

A man wielding a knife has tried to attack Finnish Prime Minister Jyrki Katainen in the southwestern town of Turku, but was swiftly arrested by police, the prime minister's office says.

"Prime Minister Katainen's security men have apprehended a person who had brought a sharp weapon to Prime Minister Katainen's electoral meeting in Turku," said the statement on Monday.

"The Prime Minister was not injured and the program will continue as planned."

Security guards quickly swooped in to protect Katainen, 41, and removed him from the scene. He returned shortly afterwards to resume campaigning.

A young "dishevelled"-looking man had approached the prime minister to shake his hand, saying he was in a difficult situation and needed help, newspaper Hufvudstadsbladet reported.

"Then the man went down on his knees, pulled out a knife and said something about killing," photographer Robert Seger, who witnessed the event, told the newspaper.

Katainen had been discussing taxes on diesel and the taxes paid by the elderly before the incident.