Saudi Arabia has threatened non-Muslim residents with expulsion if they fail to respect the rules of Ramadan in public.

The authorities have cautioned people not to smoke, drink or eat in public from sunrise to sunset during the month which began on 20 July.

Non-Muslims have been told to "show consideration for feelings of Muslims" and "preserve the sacred Islamic rituals" in the country; otherwise, their work contracts may be cancelled resulting in their expulsion, according to an Associated Press report.

According to official figures, the Sunni-dominated kingdom has around eight million expatriates, including people from the West and Asia.

The announcement appears to reflect concern that the growing number of foreign-born non-Muslims in Saudi Arabia may undermine the traditions of Islam.

The warning to non-Muslims comes as no surprise to some. "When you look around, nothing has changed and suppression has not changed. Expatriates are always at risk of expulsion for the least offence in the kingdom," says Waleed Aboul Khair, an activist who is facing trial for "tarnishing the kingdom's reputation" by supporting women's rights and other related issues, according to the AP report.

Some of the highest authorities in the kingdom are believed to be strict religious adherents, including the newly appointed prince.

The kingdom is also extremely wary of the recent popular uprisings in Egypt, Tunisia, Libya and Yemen.

The oil-rich Saudi kingdom prefers to keep the lower strata of society happy by giving them sops. Restive Shiite Muslims are kept in check, and a delicate balance between conservative and moderate Muslims is maintained.

This year, Saudi Arabia will send women athletes to the London Olympics for the first time.