ADEN (REUTERS) - Yemeni President Abd-Rabbu Mansour Hadi remains in his base in Aden and is in high spirits after ally Saudi Arabia and other countries began attacking the Houthi rebel group opposed to his rule, an aide said.

"This operation has restored people's determination" to fight the Houthis, Mohammed Marem, director of Hadi's office, told Reuters.

"The president is in high spirits and thanks Gulf countries, Egypt, Jordan and Sudan and all countries in the region," he said, adding that the operation was directed mainly against Houthi air defences in the north of Yemen.

There have been conflicting reports on the whereabouts of President Hadi. The Associated Press earlier reported that he had fled the country by sea on Wednesday as Houthi rebels advanced to take the southern port city of Aden.

Yemen has been gripped by growing turmoil since Houthi rebels launched a power takeover in the Yemeni capital Sanaa in February and are now fighting in the port city of Aden.