Qatar's new emir congratulated Egypt's Adli Mansour on Thursday after he was sworn in as an interim leader following the ousting of Islamist President Mohamed Mursi, an ally of the country, state news agency QNA reported.
Four other GCC members, including Saudi Arabia, the UAE, Kuwait and Bahrain, had earlier sent congratulatory messages to Mansour.
Qatar was alone among Gulf states in celebrating the 2011 Arab Spring revolt that toppled former President Hosni Mubarak, a foe of Iran and a longtime ally of the Gulf states.
The energy-rich country provided billions of dollars in aid to Egypt following the ousting of Mubarak.
QNA said the Emir, Sheikh Tamim bin Hamad Al Thani, "sent a cable of congratulations" to the head of Egypt's Supreme Constitutional Court on the occasion of his taking the oath as the interim president.
The agency and Qatar-owned Al Jazeera television had earlier quoted a foreign ministry source as praising the Egyptian army's role in safeguarding Egypt's national security and said the country respected the will of the Egyptian people.
Qatar has been a major financier of the Islamist groups around the Arab World, including Egypt's Brotherhood. In addition to financial aid, the Gulf state had donated fuel cargoes over the past year to support shortages in the country.
Most Gulf Arab states, rattled by the rise of Islamists in the Middle East, watched with relief as the Egyptian army stepped in to try to end the most serious crisis in the Arab world's most populous country since President Hosni Mubarak was overthrown in 2011.
"We followed with all consideration and satisfaction the national consensus that your brotherly country is witnessing, and which had played a prominent role in leading Egypt peacefully out of the crisis it had faced," UAE President Sheikh Khalifa bin Zayed al-Nahayan said in a cable to Mansour.
Kuwait's ruler Sheikh Sabah al-Ahmad al-Sabah congratulated Egypt's interim president and people. The Kuna state news agency said Sheikh Sabah praised Egypt's armed forces for the "positive and historic role" it played in preserving stability.
Saudi King Abdullah sent a message to Mansour late on Wednesday. - Reuters