A once-mighty Saudi construction firm linked to Lebanon's prime minister Saad Hariri is finished, having left thousands of workers unpaid, sources said on Friday.

The Saudi Oger employees, most of them from abroad, suffered for months without salaries and many have already gone home.

A collapse in oil revenues that began three years ago left the kingdom unable to pay private firms it had contracted. Most were in the construction sector, chiefly at Saudi Oger and another firm, the Saudi Binladin Group.

But sources say problems at Saudi Oger, whose history in the kingdom dates back almost 40 years, went deeper and now it faces the end.

Essentially, "they are closed," said a source close to the case.

"They have a contract in Jeddah I think for a royal palace but they have nothing else."

An angry ex-employee, who asked to be identified only as Robert, told AFP that he understands Saudi Oger's last day of existence will be June 30.

"In two weeks, we will no longer talk of Saudi Oger," he said. "I have lost my future."

Since resigning from Oger in January Robert no longer has a residency permit to stay legally in Saudi Arabia, and he can't pay his children's school fees.

He says he hasn't received his salary since July last year and is owed 160,000 riyals (almost $43,000/39,000 euros)

"Really it's a big crisis," the source close to the case said.

Following negotiations between France and the kingdom, more than 200 French citizens employed by Saudi Oger received in September the equivalent of nine months' salary, paid not by Saudi Oger but by the Saudi government.

But thousands of Asian employees returned home without being paid, the source said, adding that the firm had about 38,000 workers nearly two years ago.

Under an aid plan announced by the kingdom, Saudi Arabia flew the workers home and helped to file claims in court against Saudi Oger.

"But nothing is coming," the source close to the case said.

Saudi Oger could not be reached for comment.

The company, part of the Hariri family business empire, built some of the most grandiose complexes in Riyadh, including the palatial Ritz-Carlton hotel.