ABU DHABI (AFP) - United Arab Emirates (UAE) President Sheikh Khalifa bin Zayed Al-Nahyan is "well" after an operation last month following a stroke, his brother said on Monday.

"We went through a tough time but we have overcome that," said Sheikh Mohammed bin Zayed, who is crown prince of Abu Dhabi.

"Sheikh Khalifa, may God give him long life, is well," he said.

Sheikh Khalifa, 66, who is also ruler of oil-rich Abu Dhabi, has not made a public appearance since the UAE announced that he underwent an operation following a stroke on Jan 24.

His brother stressed that the leadership of the Gulf state did not want to hide the news about the President's health problem, WAM state news agency reported.

Sheikh Khalifa's health condition is "stable and assuring", said WAM, citing Sheikh Mohammed.

Sheikh Khalifa became President of the United Arab Emirates and ruler of the oil-rich emirate of Abu Dhabi in November 2004, when he succeeded his late father Sheikh Zayed bin Sultan, who founded the Emirati federation in 1971.

Abu Dhabi sits on the bulk of the UAE's oil wealth, ranked the world's seventh largest, which makes it the wealthiest of the seven UAE sheikhdoms.

In addition to Abu Dhabi, the UAE comprises the emirates of Ajman, Dubai, Fujairah, Ras al-Khaimah, Sharjah and Umm al-Qaiwain.

Sheikh Khalifa was re-elected head of the UAE for a second five-year term in 2009 by the Supreme Federal Council, a body that designates both the president and vice-president of the Gulf state.

It comprises the rulers of the seven UAE emirates.