Brendan Rodgers is close to his second signing as Liverpool manager after the club activated the £15m release clause in Joe Allen's contract with Swansea City. The move follows an admission by the Liverpool manager that Daniel Agger could be sold but only for a "ridiculous" fee that would enable him to improve the squad.

Liverpool have already turned down a verbal £20m offer from City, informing the Premier League champions they want a £27m package that could potentially involve Adam Johnson going on loan to Anfield for the season. City consider that exorbitant for a 27-year-old, pointing out there would be little resale value, but are still hopeful a deal can be struck. The club want Scott Sinclair, of Swansea City, to take Johnson's place.

Allen has been a target for Rodgers since he left Swansea for Anfield in June, despite Liverpool signing an agreement not to raid their manager's former club for players for 12 months. Liverpool have exploited a technicality in Allen's Swansea contract that allows him to join one of five specified clubs – Liverpool among them – for £15m and, having met the price, the Wales international is free to hold talks over a move to Merseyside.

The 22-year-old midfielder has been the subject of several bids from Liverpool this summer, with Swansea previously rejecting a deal of £12m plus Jonjo Shelvey on a season-long loan. Allen's expected transfer, Rodgers hopes, will address a key part of his plans for Liverpool's midfield this season and precipitate increased activity in the transfer market at Anfield.

Agger's position may change, the Liverpool manager admitted, should City make an offer that finances several signings at Anfield, where only the £10m Fabio Borini has been added to the squad so far. Rodgers is also keen on signing the Real Madrid midfielder and Arsenal target Nuri Sahin on a season-long loan.

"There has been contact [from City] but nowhere near the valuation of what the player is worth," said Rodgers, who makes his Anfield bow against Gomel in the Europa League qualifier second leg today. "You can only consider an offer for a player like that if it is going to benefit you. You don't want to lose a top player but if it benefits you going forward and you can make two or three steps because of it – you may have to consider it.

"But we don't want to sell Daniel so unless someone comes in with a ridiculous offer, that makes you look at it and think you can benefit in one or two other areas, there is no way I want to lose one of my best players."