Gordon Brown has made his first visit to Northern Ireland since Tony Blair left office.
The new prime minister is meeting with Irish taoiseach Bertie Ahern and leaders from the devolved governments across the UK for the first meeting of the British Irish Council (BIC).
The council facilitates east-west cooperation and focuses on policies that benefit from cooperation between the UK and Irish governments.
Today's meeting, hosted by Northern Irish first minister Ian Paisley and deputy first minister Martin McGuiness, is the first BIC meeting since devolution was restored to Northern Ireland.
BIC and the North-South Ministerial Council (NSMC) were both set up under the Good Friday Agreement to maintain links between the nations.
The NSMC meets tomorrow in Armagh. The Democratic Unionist Party had demanded a BIC meeting before they would attend the NSMC, citing concerns the east-west relationship was being phased out.
Ahead of the meeting, Mr Brown said he was "pleased with the co-operation that had made devolution in Northern Ireland possible" and hopes the meeting will build on recent political gains.
Mr Brown said he and Mr Ahern will discuss terrorism and security. The leaders have agreed to share biometric and other data and hope other European nations will follow suite.
Going into the talks, the prime minister spoke of the EU treaty, transportation links in Northern Ireland and concerns of drug smuggling along the Irish coast. The meeting will also cover the environment, tourism, the knowledge economy, social inclusion and minority languages.
Mr Brown said the £51.5 billion investment already promised for Northern Ireland would help ensure its economic and financial stability. The prime minister told reporters the governments want other countries to see the province as a "good place to invest".
Scotland's first minister Alex Salmond will be attending the meeting, along with Welsh deputy first minister Ieuan Wyn Jones. They will be joined by leaders of the administrations of the Isle of Man, Jersey and Guernsey.