The revelation came amid allegations from some MPs that they had been offered seats in the House of Lords under a Labour government if they would make way for younger and more favoured candidates.
Seven MPs have now stood down since the general election was called three weeks ago. The final date for the formal nomination of candidates is next week. In St Helens South, Warrington South, Cumbernauld and Kilsyth and Pontefract and Castleford, local party members were allowed to vote on replacements for John Evans, Doug Hoyle, Norman Hogg and Sir Geoffrey Lofthouse.
In the three remaining seats, Kilmarnock and Loudoun, Dudley North and Kingston-upon-Hull West, the national party will decide who will replace Willie McKelvey, John Gilbert and Stuart Randall.
The NEC panel will meet today to draw up shortlists of possible replacements. It is expected to interview and choose candidates for the English seats tomorrow and the Scottish seat on Saturday.
Among those who are still looking for seats are two MPs - Labour's higher education spokesman Bryan Davies and the Glasgow Central MP Mike Watson, both of whom were affected by boundary changes.
Jack Dromey, deputy general secretary of the Transport and General Workers' Union and husband of Labour's social security spokeswoman, Harriet Harman, has also expressed an interest in standing.
Others who were shortlisted for seats but did not win included Hilary Benn, Tony Benn's son and a former councillor, Derek Scott, an economics adviser to Tony Blair; John Harman, leader of Kirklees council; and Cath Ashton, a union convener.
Last night national party spokesmen would still not confirm how the selections were to be made.