Democratic Unionist Party MP Nigel Dodds has been struck in the head by a brick after sectarian tensions in north Belfast spilled into violence.
Rioting loyalists, some wielding swords, attacked police in a major outbreak of violence in the area. Baton rounds were fired and water cannon used by officers.
A DUP spokesman said Mr Dodds had been taken to the emergency department in a nearby hospital, believed to be unconscious. "It appears he was in and around the police lines and was talking to the police," the spokesman said. "He was hit by a brick or piece of masonry." His condition is stable.
The north Belfast violence broke out following the decision by the Government-appointed Parades Commission to bar Orangemen from walking through Ardoyne, a contested flashpoint area where dissident republicans have gathered in the past to attack police. It followed a day of peaceful Twelfth of July holiday loyal order parades across Northern Ireland, the pinnacle of loyalists' marching season.
A Police Service of Northern Ireland (PSNI) spokesman said seven officers had so far been injured in Belfast.
Shortly before he was hurt, Mr Dodds said: "This sort of situation here creating a bottleneck at this junction, the Parades Commission decision to block it here, this is the inevitable outcome.
"The police were well aware that was the danger the Parades Commission had put them in. I would appeal for everybody to stay calm, not to get involved in violence. The Grand Lodge have made it clear they do not want violence and the people who want to engage in violence should desist immediately."
Loyalist bandsmen, many highly intoxicated, played sectarian tunes at police lines while bricks and bottles were thrown.
At one point a rioter broke down a section of wall and threw it at police shields. Others used sticks and pieces of drainpipe to batter police vehicles while some danced on top of the force's Land Rovers and tried to rip off protective plating.
In East Belfast, police confirmed they also came under attack with a sword and missiles and water cannons were deployed. Two arrests were made.