DUBAI (Reuters) - Al Qaeda chief Ayman al-Zawahri on Thursday urged Saudis to rise up against the kingdom's ruling Al-Saud family, suggesting they draw inspiration from uprisings that have deposed leaders across the Middle East and Africa in the past year and a half.

Speaking in a video clip that was posted on an Islamist website, Zawahri, who took over the leadership of al Qaeda after Osama bin Laden was killed in Pakistan just over a year ago, said:

"Muslim brothers in the land of the holy mosques, a year has passed since the uprising of the Arab people against their dear brothers why do you still accept to be ruled by the Al Saud family. They are one of the worst corrupt governments who steal your money," he said.

"Why don't you rise up (against the Al Sauds) as you are the companions of the Prophet," he added.

Saudi Arabia has been spared the mass protests that have forced four Arab heads of state out of office, partly thanks to a big public spending package announced by the world's largest oil exporter early last year.

But the kingdom's Eastern Province has seen sporadic demonstrations since March last year, and in November four people were killed, according to the Interior Ministry and activists.

Protesters' demands have so far focused on political reform in the mainly Sunni kingdom, with calls to improve life for the country's Shi'ite minority and to release political prisoners.

Security forces have arrested and released around 500 people over the protests, and are currently holding 80 people, according to activists.

(Reporting by Amena Bakr; Editing by Andrew Osborn)