Updated

Five dissidents were arrested and charged with a range of serious and rarely invoked terror offenses, Northern Irish police said Friday.

Five men aged between 33 and 47 were charged with offenses such as conspiracy to murder, conspiracy to cause an explosion, preparation of terrorist acts and collecting information of use to terrorism.

Northern Irish police said three of the men were arrested in Lurgan, County Armagh, Northern Ireland, on Monday as part of a "proactive investigation" into dissident republican terrorist activity. The other two were arrested Saturday in Carrickmore and Omagh, Northern Ireland, as part of the same investigation.

Police said some of the charges have seldom been used in the past in Northern Ireland.

British intelligence has stepped up efforts in Northern Ireland recently. And law enforcement officials believe Irish dissidents could pose a threat to the Olympic games, which will be held between July 28 and August 7. The Olympic torch is passing through one of the most heavily bombed streets in Northern Ireland in early June.

But a British official said the men arrested Monday are not believed to have been planning attacks on the Olympics, torch relay, or Queen Elizabeth II's Diamond Jubilee celebrations this year.

The official, who spoke on condition of anonymity because of the sensitivity of his job, said the charges were still significant as Irish dissidents were rarely charged with preparation of terrorist acts. He said the operation showed that Britain was using techniques to fight threats posed by groups such as al-Qaida to tackle problems in Northern Ireland.

Last fall, a Lithuanian judge found an Irish man guilty of trying to buy weapons and explosives in a six-year sting orchestrated by Britain's domestic spy agency MI5 — a case that drew attention to a hardcore Irish Republican Army splinter group's plans to spread terror to London.

Judge Arunas Kisielus of the Vilnius Regional Court sentenced Michael Campbell — a 39-year-old with alleged links to the Real IRA group — to 12 years in prison for weapons offenses and supporting a terrorist group.

The five recently arrested men will appear in court Saturday. Police said another man and a woman who were arrested May 12 as part of the same investigation are still in custody.