Stormont House Agreement: David Cameron says NI leaders must deliver
David Cameron has said it is vital that Northern Ireland's political leaders deliver on their side of the Stormont House Agreement.
The prime minister was speaking after holding talks with Irish Prime Minister Enda Kenny at Downing Street.
Asked if he thought the parties could find a resolution, Mr Kenny said that everything was possible in politics.
Mr Kenny also said Dublin wanted Britain to remain an active and central player in the European Union.
Mr Cameron's plans for a renegotiation and referendum of its EU membership were discussed during the meeting.
The Irish government is concerned about the negative impact of a UK withdrawal from the European Union.
Mr Kenny confirmed that he had also raised a number of issues related to the legacy of the Troubles, including the Ballymurphy killings, the Kingsmills shootings, and the murder of Belfast lawyer Pat Finucane.
Mr Cameron offered the UK's official sympathies to Mr Kenny over the deaths of Irish students in the tragedy in California.
The Irish prime minister said he shared the anger expressed by the former Irish President Mary McAleese about the article in the New York Times that criticised the behaviour of Irish students on J1 visas so soon after the collapse of the balcony in Berkeley.
Mr Kenny arrived in London on Wednesday night and attended a banquet.
The event marked the 200th anniversary of the Battle of Waterloo, where it is estimated one third of the Duke of Wellington's army were Irish soldiers.
On Thursday morning, Mr Kenny went to a centre in London dedicated to the survivors of abuse at the Magdalene laundries.
He then travelled to Downing Street.
BBC Northern Ireland Political Editor Mark Devenport said there was evidence both governments were losing patience with how the impasse over welfare reform and the budget was frustrating the implementation of the Stormont House Agreement.
On Wednesday, Mr Kenny's predecessor as prime minister, Bertie Ahern, told the BBC a British withdrawal from the EU would be senseless and would have a hugely negative effect on Northern Ireland.
In an interview for the World at One, Mr Ahern said it would take Northern Ireland back light years and jeopardise much of the trade and investment so vital to resolving outstanding differences.
Mr Ahern also said that if David Cameron tried to unpick EU treaties, he would not achieve the changes he wants in time to hold an early referendum.
The Public Expenditure and Reform Minister, Brendan Howlin, said Ireland wants Britain to remain in the EU and there are serious concerns about a possible British exit.
He said, for the first time, Ireland would not stay neutral in a British referendum but would express its views clearly.
Mr Howlin said the government has started work to analyse the possible implications of a British withdrawal.
Mr Cameron has been holding talks with other EU leaders to try to win support as he negotiates a new relationship with the EU.
David Cameron is to continue to make the case for the UK to overhaul its relationship with the European Union.
As well as meeting Mr Kenny, the prime minister will also host European Parliament president Martin Schulz.
Mr Cameron has said he wants to speak to all his 27 EU counterparts and other key players to explain his renegotiation aims ahead of a summit next week.
Senior Tory MPs will also outline their demands for EU changes on Thursday.
Mr Cameron has said he hopes to secure a "better deal" for the UK in Europe and then ask the British people whether they want to remain part of the EU in a referendum before the end of 2017.
The UK's position will be collectively discussed by EU leaders for the first time at the European Council summit starting on 25 June.