MILAN (AFP) – The four partner countries in the Eurofighter consortium were on Friday due to sign a contract on production of the first part of the third tranche of the aircraft, sources said Thursday.

"The contract will be signed tomorrow (Friday) in Germany," said an Italian defence ministry source.

"It will be signed at the Eurofighter consortium headquarters at Hallbergmoos, near Munich," an industry source added.

The contract, worth about eight billion euros (11.2 billion dollars), was for 112 of the 236 planes in the third tranche, the source added.

Britain, Germany, Italy and Spain decided to split the order for the third tranche into two parts for budgetary reasons after a rise in the cost of materials saw the bill shoot up.

The Eurofighter is a multi-purpose combat jet developed by a European consortium comprised of the aerospace group EADS, BAE Systems of Britain and the Italian group Alenia/Finmeccanica.

Partners countries in the consortium -- Britain, Germany, Italy and Spain -- divided work on the plane in 1998 according to the number of aircraft each country planned to buy, with a total of 620 orders booked in three stages through to 2017.