Husni Mubarak has delegated power to his prime minister during his absence.

During the operation on Monday, surgeons will insert a microscopic endoscope in Mubarak's lower back to remove displaced cartilage, doctors said on Saturday.

It is normally a simple procedure but it follows persistent rumours about the health of the 76-year-old Egyptian president, who has ruled the Arab world's most populous country since 1981.

During previous trips abroad, it has been normal practice for him to delegate some of his powers temporarily to a senior official, usually the prime minister, officials said.

Rumours

But Mubarak has never appointed anyone as a long-term vice president - the route to the presidency in the last two transfers of power in Egypt, in 1970 and 1981.

If he died, the speaker of parliament would take over as interim head of state while power brokers decide on a successor to be endorsed by popular referendum.

Rumours about Mubarak's health arose after he postponed meetings this month with Israeli Foreign Minister Silvan Shalom and then with Palestinian Prime Minister Ahmad Quraya.

But he appeared in public last Wednesday, standing and talking to reporters about Egyptian plans to help the Palestinians if and when Israel withdraws from Gaza.

Last November he collapsed briefly during a speech to parliament. Officials said that was from a combination of cold medication and fasting in the month of Ramadan.