In a statement released tonight the PSNI claimed the blast bombs were thrown by masked men in the Lower Newtownards Road area.
"The blast bombs thrown in the east Belfast area earlier this evening were thrown by masked men from the area of Pitt Park at police lines on the Lower Newtownards Road," a spokesman said.
Disorder has again erupted avross East and North Belfast with police coming under attack with petrol bombs and other missiles.
Up to four (psni) officers injured.
Democratic Unionist Party MLA for North Belfast William Humphrey described the pipe bomb attack as an attempt to kill.
– Democratic Unionist Party MLA for North Belfast William Humphrey
This nail bomb was not only a deliberate attempt to further inflame tensions in this area but was an attempt to cause death or serious injury. Fortunately despite this indiscriminate weapon exploding, no injuries were sustained.
Local people have already suffered enough as a result of the trouble within the area. There is absolutely no justification for violence from any quarter, and I would hope that this incident will be treated with the utmost seriousness.
Theresa Villiers, Secretary of State for Northern Ireland, also condemned the "deplorable attack" on police officers.
The Police Service of Northern Ireland has closed a number of roads in Belfast after bombs were thrown at officers in a fourth night of protests.
Due to large protest of several hundred people Twaddell Ave Nth Bt is currently blocked to traffic. Motorists advised to take avoid area
Police are currently dealing with public disorder in the Lower Newtownards Road area of East Belfast this evening.... http://t.co/iDM8DM3B0u
Crumlin Rd in North Belfast has been closed between Tennent St and Twaddell Ave. Motorists are advised to avoid the area.
An improvised explosive device was hurled from the nationalist Brompton Park area of Ardoyne and exploded after striking an armoured police vehicle just after 5pm.
There were no reports of any injuries.
Witness Sam Coulter, who was yards from the explosion at a loyalist protest, said it was fortunate no one was hurt.
– Witness Sam Coulter
We were standing having a peaceful protest when all of a sudden there was a bang and the next thing we heard the 'tinkle, tinkle, tinkle' of nails dropping on the ground.
I think it was directed at the protest - police were at the other side of the road behind a Land Rover. Luckily nobody was hurt - just a bit of a bang to the ears.The place is in lockdown now with police doing sweeps of the area to gather evidence.
This won't put us off our protest - we are still here.
Four improvised 'blast bombs' and a pipe bomb packed with nails have been thrown towards police lines in north Belfast.
– Police Service of Northern Ireland spokeswoman
Police are currently dealing with public disorder in the Lower Newtownards Road area of east Belfast this evening.
At least four blast bombs and several petrol bombs have been thrown at police. There are no reports of any injuries at this stage. Water cannon has been deployed and one AEP (attenuated energy projectile) round has been fired by police.
Police would appeal for calm in the area and would call on those with influence to do what they can to help restore calm."
Violence has erupted in east Belfast with at least four improvised explosive devices thrown at police.
Several petrol bombs were also hurled after disturbances broke out but there were no reports of any injuries, the Police Service of Northern Ireland said.
At least one plastic bullet was fired and water cannons have been deployed to quell the disorder.
It is the fourth consecutive night of trouble in parts of Belfast.
Police have warned that more people are expected to be arrested once video footage is analysed, as riots continued in Belfast for a third successive night.
At least six petrol bombs and other missiles were thrown at police on Sunday night.
Cars along with industrial bins were also set alight in north Belfast as clashes continued.
The Police of Northern Ireland said one officer had been injured in the riots, which stem from a decision to ban a Orange Order parade passing through the nearby republican Ardoyne area.
A special sitting of Belfast Magistrates' Court was held yesterday with plans in place to keep courts open if clashes continue.
Loyalist protesters have attacked police for a third successive night in Belfast.
Trouble again flared in the Woodvale Road area in the north of the city as the fall out from a decision to ban a controversial Orange Order parade passing through the nearby republican Ardoyne area continued.
Hundreds of loyalists were involved in a tense stand off with riot police throughout the evening, with disorder finally breaking out around 10.30pm.
Petrol bombs and a range of other missiles were thrown at police, who responded by firing baton rounds.
The Police Service of Northern Ireland (PSNI) said one officer had been injured in the initial clashes.
There is a peaceful loyalist protest ongoing in north Belfast. On the other side of Ardoyne roundabout, a group of nationalists are watching on.