LONDON (Agencies) - Gerry Adams and Martin McGuinness held lengthy negotiations with the former Irish prime minister Bertie Ahern to save the Northern Ireland peace process in the full knowledge that the IRA was planning to carry out the biggest bank robbery in its history, according to leaked US cables passed to WikiLeaks. Ahern, who was instrumental in drawing up the 1998 Good Friday agreement, judged that the two Sinn Fein leaders were aware of plans for the 26.5m pounds Northern Bank robbery in 2004 because they were members of the IRA military command with a deep knowledge of its operations. The US cables also reveal that: The Irish government believed Britain had a valuable source of information at a senior level in the republican movement. Adams argued that the IRA would have to be taken out of the equation during negotiations which led the organisation to declare a formal end to its armed campaign in July 2005. The revelations are published as Adams seeks to broaden Sinn Feins appeal in the Irish Republic. The Sinn Fein president is abandoning his Westminster seat to stand in the forthcoming general election amid hopes of a breakthrough as voters register anger with Irelands mainstream political parties after the country was forced to apply to the EU and IMF for a bailout. Aherns concerns about Sinn Fein and the IRA are highlighted in cables which describe a challenging period in the peace process as London and Dublin sought to restore the power-sharing executive in Northern Ireland. Unionist suspicions about the intentions of the republican movement were fuelled when the IRA robbed the headquarters of Northern Bank in Belfast in December 2004. In a cable on February 4, 2005, two months after the robbery, the US Ambassador to Dublin, James Kenny, reported that a senior Irish government official told the embassy of the taoiseachs concerns about Adams and McGuinness. The cable claimed the official in the department of justice told the ambassador that the GOI [government of Ireland] does have 'rock solid evidence that Gerry Adams and Martin McGuinness are members of the IRA military command and for that reason, the taoiseach is certain they would have known in advance of the robbery. In another cable on June 1, 2005, six months after the robbery, Kenny reported that Ahern had raised his concerns with Mitchell Reiss, the US envoy to Ireland. The cable says: The taoiseach believes Sinn Fein leaders were aware of plans to rob the Northern Bank even as they negotiated with him last fall. Publicly, he has been unprecedentedly critical of Sinn Fein and, until recently, greatly reduced private contacts as well. The cables indicate that in private Ahern and officials used language which was slightly blunter, though consistent, with the public pronouncements of the former taoiseach, who told the Irish parliament, the Dail, he believed Sinn Fein had negotiated in bad faith. Ahern told the Dail on February 2 of a meeting with police chiefs on both sides of the Irish border. They believe that a number of operations which took place during 2004, not just the Northern Bank robbery, were the work of the Provisional IRA and would have had the sanction of the army council and be known to the political leadership. Sir Hugh Orde, the former chief constable of the Police Service of Northern Ireland who met Ahern, accused the IRA of carrying out the robbery. In what was then the largest cash robbery ever carried out in the UK, a group of armed men held the families of two bank officials hostage while the officials were forced to hand over sacks filled with millions of pounds in cash to terrorists at the bank. Nobody has been convicted of any offence in relation to the actual robbery. Ted Cunningham, a Cork-based financial adviser, was found guilty last year of laundering more than 3m connected with the robbery.Adams has consistently denied being a member of the IRA. McGuinness has admitted being a member in the 1970s.