Ukip will spell out a specific commitment to re-open Manston Airport when it launches its election manifesto tomorrow.

The party manifesto will make an explicit reference to Manston, saying that it is ideally placed to address the lack of airport capacity in the south east.

Party sources say they want to send a signal that it strongly supports Manston, which was closed last May.

The airport has become a key issue in the electoral battle being waged in South Thanet.

The Conservatives last week brought down transport minister John Haynes to announce that consultants had cleared the way for Thanet council to pursue a compulsory purchase order for Manston.

Now Ukip hopes to trump that by saying in its manifesto that "part of the solution to address the lack of airport capacity in the south east is to re-open Manston Airport."

It will add: "Manston is ideally placed to take low-cost airlines and freight only aircraft; it is close to the railway network, enjoys good connections to Ashford International; will release additional capacity in the region and take pressure off other airports."

Ukip leader Nigel Farage, who is standing in the South Thanet constituency, said: "Despite all the rhetoric, there is no mention of Manston Airport in the national Tory or Labour manifestos.

"We are the only party so committed to bringing Manston back, that it forms a core part of our national transport strategy, and is fully endorsed by the party as a whole."

Polls put the fight for South Thanet increasingly close, with one saying the Conservatives had edged ahead of Ukip.