The Kingdom of Saudi Arabia has expelled almost 40,000 Pakistani migrant workers in the last four months, local media has reported.

Over 39,000 people have been deported since October 2016 over visa violations and security concerns, the Saudi Gazette reported, citing unnamed interior ministry officials. As well as crimes including drug trafficking, forgery and theft, an unknown number of those removed from the country were suspected to have links to Isis and other extremist groups, the paper said.

The mass deportations come after a year of strikes and other unrest in the kingdom due to unpaid wages following the oil market’s decline and subsequent blow to the Saudi economy.

Official Saudi statistics say that 243,000 Pakistanis were deported between 2012 - 2015. Mass deportations of migrant workers - which Human Rights Watch and other rights organisations say often involve illegal beatings and detainment in poor conditions - are fairly common.

2010 census figures show that 8.5 million of Saudi Arabia's 27 million strong population, or around 30 per cent, are foreign nationals.

According to a 2014 European University Institute report, there are approximately 900,000 people of Pakistani nationality currently employed in Saudi Arabia’s vast construction industry and other low-paid service jobs.

In Mecca in January, dozens of expatriate workers, mostly from poor Asian and Middle Eastern countries, were beaten and jailed over public protests against unpaid salaries that turned violent.