CAIRO, May 13 (Xinhua) -- Leaders across the Middle East on Friday mourned the passing of President of the United Arab Emirates (UAE) Sheikh Khalifa bin Zayed Al Nahyan and spoke highly of the late ruler of the Emirate of Abu Dhabi, who died at the age of 73 after years of illness.

"I deeply mourn with sorrow the loss of President of the United Arab Emirates Sheikh Khalifa bin Zayed Al Nahyan, who passed away after a long journey of giving," said Arab League Secretary-General Ahmed Aboul-Gheit in a statement on Friday.

Sheikh Khalifa served the joint Arab work effectively and prioritized the Arab rights and interests, he said, adding that the UAE remained during his life a model of solidarity with all the Arab nations.

"On my behalf and on behalf of the people of Egypt, I offer the leadership and people of the UAE our sincere condolences for this great loss," he added.

The pan-Arab body chairman declared official mourning for three days and flags flying at half-mast.

Kuwaiti Emir Sheikh Nawaf Al-Ahmad Al-Jaber Al-Sabah expressed heartfelt condolences on Friday over the death of the UAE president, and announced a 40-day mourning period, the Kuwait News Agency (KUNA) said.

Arab and Islamic nations lost a great leader who dedicated his life to the service of his people, the Kuwaiti emir said.

Meanwhile, Kuwait's national flag will fly at half-mast and government departments in the country would be off duty for three days starting from Friday.

Neighboring Gulf countries Bahrain and Oman have also announced an official three-day mourning.

Lebanese President Michel Aoun on Friday extended his condolence over the death of the UAE president and his government declared nationwide mourning.

Aoun said that Arab countries will miss Sheikh Khalifa who carried their just causes and Lebanon will miss a sincere brother who loved the Lebanese population.

It is notable that the Israeli president and prime minister also mourned on Friday the death of the UAE president.

"Sheikh Khalifa's bold leadership contributed so much to the advancement of the UAE and its people and to the growing partnership between our countries," Israeli President Isaac Herzog said in a statement.

"His life's work pushed the Middle East to new horizons of prosperity and cooperation," he noted.

Israeli Prime Minister Naftali Bennett tweeted in Arabic that "the great legacy and giving of the late Sheikh Khalifa have been greatly appreciated in Israel. The state of Israel stands with the UAE in these difficult hours."

The UAE Ministry of Presidential Affairs on Friday announced the President of UAE Sheikh Khalifa bin Zayed Al Nahyan passed away earlier in the day and confirmed there will be 40 days of official mourning with flags across the UAE drawn at half-mast, and the work of all UAE ministries at the federal and local levels, as well as those of the private sector, will also be suspended for three days.

Sheikh Khalifa first assumed the federal constitutional authority as the second president of the UAE and became the 16th ruler of the Emirate of Abu Dhabi on Nov. 3, 2004, succeeding his late father Sheikh Zayed bin Sultan Al Nahyan, the country's founder.