Hung parliament: Lib Dem MPs want more Tory deal detail
David Laws MP: Lib Dems "have asked for clarification" from Tories
Lib Dem MPs are seeking more assurances on their key priorities - such as voting reforms - from the Tories, after a two-hour meeting with Nick Clegg.
He was updating his MPs, whose support he will need for any deal, on three days of talks with the Conservatives about forming a government.
Senior Lib Dem David Laws said they had also urged him to "listen" to Labour.
Mr Clegg also held meetings with David Cameron and with Gordon Brown - who is due to make a statement shortly.
The meetings were arranged after what the the official Tory and Lib Dem negotiating teams called good "progress" was made in negotiations.
Speaking after a two-hour meeting of all Lib Dem MPs, chief negotiator David Laws said they had asked Mr Clegg to seek clarification from the Conservatives on various policies - including education funding, fair taxes and voting reforms.
The MPs had also asked for them to "continue to listen to the representations coming from the leader of the Labour Party".
Sunday: Lib Dem and Tory teams met for six hours. Meanwhile Nick Clegg met Gordon Brown at the Foreign Office.
Later in the evening David Cameron and Mr Clegg met for 45 minutes in Parliament
Monday, 0800 BST: Markets open
Monday morning: 30 min phonecall between Clegg and Cameron
But he said they had agreed the priority was forming a strong government in the national interest.
BBC News Channel chief political correspondent Laura Kuenssberg said she had been told by Lib Dem sources that the Conservative offer did contain quite far reaching reforms to the political system - and some tentative plans for reforming the voting system.
But it did not include proposals for the "alternative vote" - on which Labour has promised a referendum.
The Conservatives won the most MPs and the most votes in the election - but failed to win an outright majority and are seeking Lib Dem support to form a government.
But the Lib Dem negotiating team has also been in what appear to be parallel talks with Labour - meeting Lord Mandelson, Ed Miliband, Ed Balls and Lord Adonis in secret at the weekend, BBC political editor Nick Robinson said.
BBC Political Editor Nick Robinson said he could not get any official comment from the Lib Dems or Labour about what was discussed but it showed Labour had not given up on the idea of doing a deal with the Lib Dems, even though the Lib Dems do not want Gordon Brown to remain prime minister.
He said senior Cabinet figures had suggested Mr Brown could remain as PM for a transitional period, but announce his intention to stand down by a specified future date.
If electoral reform is the stumbling block to any deal with the Tories, Gordon Brown is the block to any Lib/Lab deal
It is not yet known whether that was discussed during Mr Clegg and Mr Brown's second face-to-face meeting in 24 hours.
Mr Clegg, who told the BBC he was "almost, almost" there on making a decision, also held private talks with Mr Cameron at lunchtime as well as a 30-minute phone conversation.
The Conservative front bench have also met and there will be a wider meeting of all Tory MPs at 1800 BST. The Lib Dems' governing body, the federal executive, is also due to meet. It would also have to approve any deal, under Lib Dem rules.
Before talks on Monday morning, Mr Clegg told reporters he understood people were anxious to know what was happening but said all parties and party leaders were "working flat out around the clock".
He said they would arrive at a decision "as quickly as possible" but said he hoped people would understand they wanted to get the decision right rather than come to an arrangement that "won't stand the test of time".
LIB DEM's 'TRIPLE LOCK'
Win support of 75% of MPs
Win support of 75% of ruling federal executive
If not - call a special conference
If still insufficient support - postal ballot of all members
William Hague, one of the senior Conservatives involved in the negotiations, told reporters the talks were "going well" and they were talking about "some specific ideas and proposals". He said they were "optimistic" about making progress soon.
Leaving the talks an hour and a half later, he said they had made "further progress" but said they had to go back to Mr Cameron to update him and Tory MPs and peers.
Both sides have stressed that the stability of the British economy is key to any deal.
David Dimbleby will present a BBC election special on BBC One at 2030 BST. It will also be streamed on the BBC News website.
There had been some fears that the pound and shares would suffer if a deal was not done by the time markets opened on Monday.
But once trading began, the FTSE 100 index of London's leading shares leapt more than 4% - suggesting traders saw the EU deal over a fund to stop the Greek debt crisis spreading as much more significant.
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