Commons leader Peter Hain has been pelted with eggs and his aide punched during a pro-hunt demonstration at Oxford University on Wednesday night.
Mr Hain condemned "thuggery"
Mr Hain, who said violence and thuggery would not help the arguments of pro-hunt groups, had to be given a police escort after making a speech.
He was confronted by more campaigners at the city's railway station. Thames Valley Police made two arrests.
The incident came after peers voted for licensed hunting instead of a full ban.
The vote put the House of Lords on a collision course with MPs, who may use the Parliament Act to force through a ban.
Mr Hain has been targeted before by hunt protesters when his house was blockaded ahead of the Labour conference.
On Wednesday evening, he was jostled by a crowd of about 40 protesters as he arrived at the Oxford University Labour Club.
A couple of the protesters managed to get inside the
meeting, despite tight security, and ran at the minister, throwing eggs from a distance of around
half a metre, said Mr Hain's spokesman.
Police brought the campaigners to the ground and escorted Mr Hain, covered in egg, out of the building but he was met by 15 protesters at the railway station.
A 32-year-old man was arrested on suspicion of threatening behaviour, and a 25-year-old man was arrested on suspicion of threatening behaviour and assault, according to the police.
"If the hunters wish to persuade people of their case, it should be by the force of their arguments, not
by physical violence and thuggery," said Mr Hain.
It is not yet known whether the protest was organised by any specific pro-hunt campaign group.
On Wednesday, a fox was also caught inside Parliament but it is not yet known whether it was part of a protest stunt.
The animal did not get into the chamber of either House of Parliament.
A spokeswoman for the Commons said: "We know that a fox got in early this morning. It is not yet known how he got in.
"He was captured swiftly by Parliamentary staff and cared for and fed and watered until the RSPCA turned up to care for him."