Makkah, Saudi Arabia,: Saudi Arabia will invite tenders next year for a $16.53-billion metro network in Makkah, to ease congestion in the city, particularly during the annual Haj pilgrimage, the city’s mayor said on Wednesday.

Known as the Makkah Metro, the 62 billion Saudi riyal ($16.5 billion) project calls for the construction of a four-line rail network and a call for tenders is due to be launched in January 2013, mayor Osama Al Bar said.

“Studies have been finalised,” he told AFP, adding that the government endorsed the project in August.

Makkah received this week around 2.5 million pilgrims for Haj and its resident population is due to rise to three million in 20 years.

Al Bar said that the metro network will cover 182 kilometres when the four lines are completed in 10 years.

The first stage is due to be completed in three years and will cover 122 kilometres, he said.

Authorities have invested billions of dollars to upgrade infrastructure and services to cope with the ever-increasing numbers of pilgrims who visit Saudi Arabia for Haj, and for Umrah, the lesser pilgrimage done year round.

In 2010, Saudi Arabia inaugurated its Mashair Railway, which cost $1.8 billion to transport pilgrims between the holy sites of Mina, Muzdalifah and Arafat, just outside Makkah.

The much larger Haramain High Speed Rail is set to stretch 444 kilometres between Makkah and Madinah, through the Red Sea city of Jeddah.

The Makkah Metro is expected to connect to both lines.