The 75-year-old multi-billionaire, who is considered the architect of the Swiss People's Party (SVP)'s soaring popularity, was leaving a political roundtable discussion at a Zurich hotel Saturday afternoon when an
unidentified man accosted him, the SonntagsBlick weekly reported.
Blocher, who was walking down one of the hotel's corridors with his wife after a debate on Switzerland's relationship with the EU, told the paper the man had asked him if he remembered him before swinging a punch at him.
The Swiss ATS news agency said police gave the attacker's age as 81. Security guards tackled the man and pushed him up against a wall, at which point a knife he was carrying fell to the ground, SonntagsBlick reported.
Zurich police, who could not immediately be reached for comment, arrested the man, it said.
The attacker appeared "disoriented", said Blocher, who stood down earlier this year as vice president of SVP, Switzerland's largest party.
The politician is widely credited with bankrolling the party and transforming it from a rural group into a powerful political machine anchored to the hard right.
He helped cement SVP's brand of populist nationalism, with its virulent campaigns against immigration, the European Union and Islam.