Workers at one of Saudi Arabia’s largest employers set fire to buses on Saturday amid protests at being laid off and told to leave the kingdom without being paid for several months work.

Footage uploaded to YouTube showed employees of the Binladin Group protesting outside the construction company’s offices in Mecca province, and setting fire to several buses.

Saudi daily Okaz reported that fires on seven buses in Mecca had been extinguished without any fatalities, adding that local authorities had launched an investigation into the incident.

However, the newspaper did not mention the cause of the fire, which was by angry former Binladin employees.

The protesting workers are among 50,000 foreign labourers who have been sacked by the private company as the kingdom’s revenues have declined due to low oil prices, which have forced government spending cuts.

Saudi daily al-Watan reported on Friday that Binladin had given the sacked foreign workers a permanent exit visa to leave the country but many of them do not want to leave because they claim not to have been paid properly.

Watan said some of the workers had not been paid in at least four months, and that they are now holding daily protests in front of the company’s offices.

The mass sacking by Binladin constitutes a 25 percent reduction of its total 200,000 workforce, according to its LinkedIn page.

The company, which was established in 1931 by the father of the late al-Qaeda leader Osama Bin Laden, is one of Saudi Arabia’s largest employers and it has been responsible for large construction projects including building towers in the capital Riyadh, and universities and airports in the western port city of Jeddah.

But the company has reportedly been suffering from debts of up to $30bn and it has been engaged in a series of pay disputes with workers, which in March led to protests outside their offices in Riyadh.

Binladin may also be feeling the pinch because of a catastrophe at one of its projects last year, when a crane in the holy city of Mecca collapsed and killed 107 people.

The incident prompted the government to suspend the company from future contracts, and led to an investigation by the finance ministry into its existing state projects.

Saudi Arabia has been forced to cut its government spending as oil prices, which account for the majority of the kingdom’s income, have plummeted by up to 70 percent in two years.

The Binladin group has not issued a statement about the reported sacking and the pay dispute with workers.