THE IRA leadership is believed to have given the go ahead for the London bombing as long as a month ago, according to security sources in Northern Ireland.
RUC and Garda sources appear to agree that an IRA unit based in the Republic, led by two Northern IRA men, carried out the attack.
Two men named as being involved in planning the attack are also suspected of having directed previous bomb attacks in Britain. One was in prison in Northern Ireland until the mid 1980s and the other has been living in Dublin since the 1970s. Neither is a well known Sinn Fein member, though one has appeared at Sinn Fein events.
The same IRA unit used bombs assembled in the Border area to launch the last series of bomb attacks in London and it is believed the same type of operation was used in the latest attack.
A two ton bomb assembled by this unit was intercepted at Heysham ferry port in Lancashire two months before the IRA ceasefire was called.
It was suspected at the time the IRA was transporting the bomb 10 London in preparation for the (ending of the ceasefire. It is thought the Canary Wharf bomb was constructed in recent weeks in the Border area and transported to London, possibly through a northern ferry port.
Garda and RUC Special Branch activity is being stepped up considerably with officers, on both sides of the Border who had been diverted to ordinary crime duties since the August 1994 ceasefire, being directed back to an anti terrorist role from yesterday.
The State's response to the ending of the ceasefire is being considered by senior Department of Justice officials who were briefed by senior gardai on Monday.
There was no indication last night of any major security initiative. Gardai are attempting to find out if the IRA intends to launch further attacks. Both the Garda and RUC were caught completely unawares by the attack.
The Minister for Justice, Ms Owen, is to address the Dail today on the crisis and the State's response.
While anti terrorist activity is being stepped up, informal links between senior Government officials and republican leaders is still expected to take place.
At least one of the Sinn Fein figures in contact with the Government officials is said, by security sources, to be in the IRA leadership, and possibly a member of its army council.
The reason for setting up the Canary Wharf attack is still unclear. However, there are strong suspicions that the threat of a split within the IRA may have been a major factor.
It still appeared yesterday that the lorry used to transport the bomb to London was stolen in Northern Ireland, fitted with false plates and a tax disc stolen from a car lot in north Antrim three, weeks ado.
The source of the telephone warning about the bomb, made to a newspaper office in Belfast at 5.30 p.m. on Friday at the same time as telephone calls to RTE announcing the end of the cease fire, is still not clear.
It is understood a hoax calf about a bomb in Heathrow Airport was made from one of the public telephones at St Mary's Bridge, Drogheda, which were removed by gardai for forensic examination on Saturday morning.