Newcastle United have knocked back an enquiry from Birmingham City for Karl Darlow, Football Insider understands.

The Championship club made a move for the 29-year-old goalkeeper as they look to strengthen ahead of the new season.

A Newcastle source has told Football Insider that the club rejected the advances of Birmingham because they wanted proven back-up to established number one Martin Dubravka.

Mystery surrounds the contract situation of the 6ft 3in keeper amid speculation his deal had been due to expire this summer.

But one report has suggest Darlow’s agreement actually runs until the summer of 2021.

That has given Newcastle the power to knock back interest in the long-serving keeper just weeks ahead of the new Premier League campaign.

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Darlow moved to St James’ Park from Nottingham Forest in the summer of 2014 as part of a double deal with Jamaal Lascelles that was worth around £7million.

There has been interest in the past few windows from clubs including Leeds, who were previously willing to pay around £4m for him.

The keeper has made 62 appearances for Newcastle and was a key player in the side that got promoted from the Championship under Rafael Benitez.

But he has been forced to play second fiddle to Dubravka over the last two years.

Darlow was an unused substitute for all but one Newcastle’s 38 Premier League matches last season and his only six appearances came in the domestic cups.

In other news, Paul Robinson has claimed Newcastle United are on the verge of brilliant signing.