The RUC says pipe bombs and blast bombs have been used in 95 attacks this year. Up to Thursday there had been 74 incidents involving pipe bombs and 21 involving blast bombs. Loyalists are believed to have been behind most of them.
Nationalists were the targeted in the two latest attacks, in Dunmurry on the outskirts of south Belfast and Derry city.
The RUC said it was treating as sectarian a nail-bomb attack on a house in Dunmurry in which a woman escaped injury. She was asleep upstairs when a device was thrown through the window of the house at Upper Dunmurry Lane just after midnight yesterday.
A car believed to have been used in the attack was later found burned out on the loyalist Seymour Hill housing estate.
Ms Patricia Lewsley, the SDLP assembly member for the area, blamed loyalist paramilitaries. "Tensions are being heightened here, particularly coming up towards the marching season," she said.
A man and his two teenage children escaped injury when the front door of a house was damaged in a pipe-bomb attack in Derry. They were in the house at Curlew Way on the loyalist Clooney estate when the device exploded in the front garden shortly after 3.30 a.m. yesterday. An RUC spokesman said it was also treating the incident as sectarian.
Meanwhile, term ended at the Holy Cross Catholic Girls Primary School in north Belfast without any end to the stand-off between nationalist parents and loyalist residents at the school's front gates.
Parents had put forward the suggestion that two or three of them could have escorted the children into the school as a token gesture but this was rejected by the loyalist residents who said no one would be permitted to use the front gates until a number of other issues were addressed.
In west Belfast, three men were arrested in an incident in which the police fired two shots at a car in New Mossley at about 2 a.m. yesterday.
In a separate incident a man was taken to hospital with a gunshot wound to his right ankle after being attacked in the New Barnsley area of west Belfast.