Saudi authorities rounded up thousands of illegal foreign workers at the start of a nationwide crackdown, according to media reports.
"Since early [Monday] morning, the security campaign got off to a vigorous start as inspectors swung into action," Nawaf al-Bouq, a police spokesman, told the Saudi Gazette newspaper.
Police carried out raids on businesses, markets and residential areas to catch expatriates whose visas are invalid because they are not working for the company that 'sponsored' their entry into the kingdom.
For a second day on Tuesday parts of the capital Riyadh were unusually empty as many expatriates stayed at home to avoid potential arrest.
Hundreds of thousands of workers have already left the kingdom following a grace period of seven months.
The government hopes that reducing the number of illegal workers will create opportunities for Saudi jobseekers.The official Saudi unemployment rate is 12 percent, but excludes a large number of citizens who say they are not seeking a job.
However, the majority of the kingdom's nine million foreigners are unskilled labourers or domestic workers, jobs usually shunned by Saudis.
Raising private sector employment in a country where most Saudis are in government jobs and where businesses employ more foreigners than locals is a major challenge.
Bouq told the Gazette that at least 1,899 illegal workers had been arrested in the Red Sea port city of Jeddah. Additional arrests included 2,200 people in Samta, 379 in the Eastern Province and hundreds of others in other cities.
In Jeddah, dozens of Indonesian workers, mostly women, staged a sit-in to pressure the authorities to hasten their
deportation, according to Arab News newspaper. The city was the scene of mass protests earlier this at the Indonesian consulate, when thousands of people were attempting to have the official status confirmed before a deadline.
Many workers cannot leave the country because they lack official papers, including passports.
For decades, Saudi authorities ignored irregularities such as working for firms that had not sponsored their visas or in trades other than those listed on their immigration documents.