CAIRO - Egyptian authorities on Wednesday banned a former prime minister and a Cabinet minister from leaving the country, a move that often preludes a criminal investigation and a possible trial, state TV said.

Prosecutors imposed the travel ban on Atef Obeid, who served as premier from 1999 to 2004, as well as long-serving Culture Minister Farouq Hosni. The restrictions also cover the head of state TV and radio, Osama el-Sheiky, as well as nine businessmen deemed to have cushy ties with the regime of ousted President Hosni Mubarak.

The restrictions are the latest legal measures taken by Egypt's military rulers against stalwarts of the former regime. Mubarak stepped down Feb. 11 after a popular uprising, handing over power to the military.

Last week, authorities arrested three other former ministers -- ex-Interior Minister Habib el-Adly, former Housing Minister Ahmed Maghrabi and ex-Tourism Minister Zuheir Garana. All three are under investigation for corruption, and had previously been banned from travel abroad and had their assets frozen.

They are among some dozen ex-ministers and businessmen who are under investigation for corruption or abuse of authority.

The protesters who ousted Mubarak in 18 days of demonstrations against his regime often mentioned the deep corruption of the government as a key reason behind their movement.

Also Wednesday, hundreds of low-ranking police officers set fire to parts of the security headquarters in central Cairo after four days of protests to demand better salaries, a security official said.

He said the protesters hurled firebombs at the building, setting parts of it ablaze. The official spoke on condition of anonymity because he was not authorized to speak to the press.

The official said soldiers tried to disperse the crowd by firing in the air, but failed.

The Interior Ministry said in a statement that the officers numbered about 500 and that most of them had been sacked earlier and were demanding their jobs back.

The statement said some of them set fire to a car parked outside the headquarters, and that the blaze spread to eight other vehicles as well as the building. It said the protesters tried to prevent fire engines from reaching the blaze but the army forced them to open the way.

Egypt is now ruled by military commanders after massive protests ousted longtime President Hosni Mubarak.