JEDDAH, March 12 (Reuters) – Top OPEC oil exporter Saudi Arabia is planning to launch tenders worth more than 17 billion riyals ($4.5 billion) this year to modernize two airports in the Gulf Arab state, an official said.

Traffic at Saudi airports has reached 30 million passengers annually and is expected to double to 60 million over the next 10 years, said Alaa Samman, director of business development at the General Authority of Civil Aviation (GACA).

In order to cater for this growth, the government wants to launch projects costing at least 55 billion riyals to overhaul airports to be completed over the next 20 years, he added.

For this year alone, GACA wants to launch tenders to build a new airport in the holy Muslim city of Medina and a commercial center near Jeddah airport.

The new Medina airport, estimated to cost between 7 billion riyals and 8 billion riyals, will increase traffic capacity to eight million passengers a year from three million.

''We plan to offer a 25-year build, operate and transfer (BOT) contract for the development of a new airport in Medina,'' Samman told Reuters. The tender will be launched in May with bids accepted until October and contracts to be awarded by December.

In the Red Sea port Jeddah, Saudi Arabia's commercial hub, authorities want to build an ''airport city'' that will include hotels, office buildings, housing units, malls and even a flight academy, Samman said.

Jeddah airport, which is a gateway for millions of Muslim pilgrims to the holy cities of Mecca and Medina, receives 18 million passengers a year and expects to see an increase of up to 30 million by 2013, Samman said.

''We have offered two large pieces of land, one is one square kilometre and the other is 1.4 square kilometres, to Saudi and foreign investors for the development of the airport city,'' Samman said. Development would cost around 10 billion riyals.

Four prequalified consortia including Australia's Land Lease Corp., Saudi's Saudi Oger and Saudi Real Estate Co. (Akaria), as well as US developer Hines, are expected to submit bids before the end of May.

The contract is scheduled to be awarded by August.