Minister for Justice Dermot Ahern has said the threat posed by dissident Republicans is as dangerous as it was at any time during the 30 years of the Troubles in Northern Ireland.

He said there was a growing escalation of major incidents since September last year - 13 in all.

Mr Ahern said it was a worrying trend because the capability of dissident groups was growing.

The minister was speaking after an explosive device was fired at a police station in Craigavon, Co Armagh, last night and a car bomb went off in Newry earlier this week.

In a separate incident last night, police came under attack and fired three baton rounds during rioting in Craigavon.

Chief Inspector Jason Murphy said he believes last night's attack was intended to kill or injure police officers.

Dissident republicans were blamed after a suspected mortar bomb was fired at the Craigavon police station. A year ago a policeman was shot dead by the Continuity IRA not far from the scene of last night's attack.

Dissidents were behind last week's murder of Ciaran Doherty, 31, in Derry as well as a number of other attacks on police stations.

Sinn Féin assembly member John O'Dowd said: ‘This attack was wrong and should not have been carried out.

'I would challenge those who claim to speak politically for these factions to tell the republican and nationalist community exactly how these sorts of activities, or indeed the recent murder in Derry, advance the cause of a united Ireland one iota.

‘The fact is they don't. A peaceful and democratic path to Irish unity exists and it is the path that the vast majority of republicans are now on.’

A viable mortar device was found close to Keady police station, south Armagh, recently.

In March last year policeman Stephen Carroll was shot dead by the Continuity IRA as he answered a call for help in Craigavon.

The amount of dissident activity across Northern Ireland has been on the rise.

The police station targeted yesterday is in the Brownlow area of Craigavon, a sprawling urban centre of housing estates and roundabouts. It was blown up in 1993 by the Provisional IRA with a nearby health centre and school. There are also business premises in close proximity.

Police received a report yesterday afternoon of a suspicious device on the nearby Tullygally Road. As a search was planned a device was fired at the station.

Officers later received reports of the device again being placed on the Tullygally Road.

The device was later declared a hoax.