London, England (CNN) -- Bomb attacks by dissidents in Northern Ireland nearly quadrupled over the past six months from the period before, a report from the Independent Monitoring Commission said Thursday.
Dissident republicans have steadily increased the number of improvised explosive devices they have deployed and detonated over the past two and a half years, the commission said. Since May, the number of devices deployed was roughly double that of the previous six months -- and the number detonated went up nearly fourfold, it said.
The findings by the commission, set up nearly seven years ago by the British and Irish governments, are in the latest and last of its biannual reports on the paramilitary and security situation in Northern Ireland.
While the number of bombings has gone up, there have been no deaths from bomb attacks and no one has suffered life-threatening injuries.
Still, the commission said, "the high level of dissident activity would undoubtedly have led to many more deaths, injuries, and destruction had it not been for the operations of the law enforcement and security agencies north and south (in Northern Ireland and the Republic of Ireland) and their ever closer cross-border co-operation."
It said that in both Northern Ireland and the Republic, about three times the number of dissidents have been charged with terrorist offenses in all of 2010 than in 2009, and the number of arrests has nearly doubled.
Dissident republicans are those who refused to accept the 1998 Good Friday peace settlement and power-sharing deal negotiated and signed by mainstream republican leaders such as Sinn Fein's Gerry Adams and Martin McGuinness.
Groups like the Real IRA and Continuity IRA broke away from the Irish Republican Army, also called the IRA, which fought for decades against British rule in Northern Ireland. The IRA agreed to a process of decommissioning under the Good Friday deal, something the dissident republicans do not accept.
The report also said the two factions of the Real IRA have been the the most active and dangerous of all such groups, conducting 18 attacks on members of the security forces and those associated with them. Each faction has its own structure and "army council," the report said.
"Together, the two were responsible for a very major campaign of violence directed particularly at members of the security forces," the report said. "It was the most serious paramilitary threat over the six months under review."
The attacks included an improvised mortar, pipe bombs, and shots fired at army and police targets. In August, a device in a hijacked taxi exploded outside a police station in Derry, causing substantial damage to property.
"During the six months under review, the two factions of (the Real IRA) remained a very dangerous and potentially lethal terrorist threat," the report said. "We are convinced that they would have taken the lives of members of the security forces if they had been able to do so in several of the attacks."
Amid the rise in the number of bomb attacks, the number of casualties from shootings and assaults over the six-month period was "considerably lower" than in the recent past, something the Independent Monitoring Commission attributed to a reduction in the amount of violence inflicted on people for anti-social behavior like dealing drugs.
"At a time when attention is rightly directed to the dissident threat, this trend should also be borne in mind," the report said.
CNN's Melissa Gray in London, England, and Journalist Peter Taggart in Belfast, Northern Ireland, contributed to this report.