Saudi security forces have arrested 28 al Qaeda militants suspected of planning "criminal acts" in the kingdom, the official Saudi Press Agency (SPA) reported on Sunday.

The suspects were arrested in Mecca, Madina, Riyadh and in an area near the country's northern borders, said SPA quoting an official source at the Ministry of Interior.

One of those arrested is a foreign resident while the rest are Saudi nationals, it said without giving further details. "The (public) interest requires that further details be withheld for the time being," it said.

The synchronised operations leading to the arrests began in mid-December, SPA said.

Saudi-owned Al Arabiya television said on Friday security forces had arrested an unspecified number of al Qaeda militants suspected of planning attacks in the country during the Muslim haj pilgrimage.

It was not immediately clear if the latest report referred to the same arrests.

Saudi Arabia, a U.S.-allied monarchy, the world's biggest oil exporter and home to Islam's holiest sites, was the target of attacks by militants linked to al Qaeda in 2003. Militants opposed to the royal family seized control of Mecca's Grand Mosque in 1979.

Interior Minister Prince Nayef has said that the arrest of 208 men last month in a raid against suspected militants was not linked to the haj.

The haj, one of the world's biggest displays of mass religious devotion, has been marred in previous years by fires, hotel collapses, clashes between police and protesters and deadly stampedes caused by overcrowding.