Former Labour Party treasury minister Steven Timms has been stabbed at his constituency office in east London.
Mr Timms (54), was taken to a local hospital but his injuries are not thought to be life-threatening, a Labour spokesman said.
Police said a 21-year-old woman had been arrested in connection with the incident which took place as the East Ham MP held a monthly meeting with constituents at a library in Beckton, east London this afternoon.
Mr Timms, who was elected to parliament in 1994 after working in the telecommunications industry and serving on a local council, held several ministerial posts under former prime minister Gordon Brown and his predecessor Tony Blair. He has lived in east London since 1979.
Mr Timms has been MP for the East Ham constituency - and previously for Newham North East - since 1994.
He has regularly spoken out against knife crime in his constituency, particularly among young people.
In 2000, a Liberal Democrat councillor was murdered by a man with a samurai sword at the offices of Cheltenham MP Nigel Jones, who was also seriously hurt in the attack.