Updated

Even before Qatar's emir Sheikh Hamad bin Khalifa al-Thani delivered his early-morning abdication speech on Tuesday, citizens in white traditional dishdashas were lining up outside the palace to swear allegiance to the new ruler, his son.

Qataris received the news with mixed emotions as the 61-year-old emir, who came to power in a coup in which he overthrew his own father 18 years ago, announced he will cede power to his son, crown prince Sheikh Tamim, 33.

"We are sad for the departure of the builder of modern Qatar but are also pleased with the continuity of (the line of) power," said Hamad al-Hijji.

The 37-year-old financial expert, accompanied by his brother, waited patiently to greet the new emir, unlike hundreds of others who turned back when they saw the vast crowds outside the palace.

Under the scorching sun, scores waited in long lines outside the large white seaside building in Doha.

Sheikh Hamad, using the tiny Gulf state's vast wealth generated by its enormous gas deposits, had transformed Qatar into a political and economic powerhouse with multi-billion-dollar investments across the world.

No official reason has been given for the abdication, although the emir is known to suffer from kidney problems.

Officials and diplomats say however that sheikh's handing over of power was not linked to health issues but rather a determination to bring a younger leadership to the fore.

Tamim's accession makes him the youngest sovereign of any of the Gulf Arab monarchies.

Hijji said he hoped the historic transition would "encourage other Arab countries to undertake similar rejuvenations" in their political systems.

Autocratic rulers in the Arab world had held power uncontested for decades until the Arab Spring revolutions that toppled regimes in Tunisia, Egypt and Libya.

By ceding power at his age, "Sheikh Hamad, concerned about the national interest, gives a lesson to other Arab leaders who cling to power," agrees a Qatari father.

The 29-year-old customs employee, who declined to be named, added that he had been inspired by the "wisdom of Sheikh Hamad" in choosing to give up power.

A young Qatari woman clad in a black traditional abaya, sitting in a coffee shop in a shopping centre on the outskirts of Doha, voiced mixed feelings.

"I am saddened by the departure of the father of this nation under whose reign I had lived and grown up," she told AFP. "But I'm reassured about the future with the enthronement of Sheikh Tamim, who is young but mature."

Abdelaziz al-Duhaimen, a 34-year-old official from the National Olympic Committee, headed by Tamim, was upbeat.

"This change offers a chance for young Qataris who, like Sheikh Tamim, are well-trained and competent enough to take new responsibilities," he said.

Tuesday was announced a public holiday in Qatar as the palace invited Qataris -- who comprise just 200,000 people out of a population of nearly two million -- to come to the palace to swear allegiance to the new emir.

On the corniche near the palace, a van decorated with Qatar's burgundy and white flags played patriotic music and anthems. The rest of the city was nearly empty.

Television footage showed Qataris, among them tribal leaders, army officers and dignitaries, pouring into the palace to greet the new emir who stood smiling next to his father.

Among those who arrived to congratulate the father and son was influential Muslim cleric Sheikh Yusuf al-Qaradawi, who embraced both.

Qaradawi is a controversial figure in the West and has millions of supporters, mostly from the Muslim Brotherhood -- which Qatar reportedly supports.

But expatriates, who make up a majority of the emirate's population, seemed indifferent.

"For us, this makes no difference. It is an internal matter and it is the same family ruling," said a Bangladeshi taxi driver.

The allegiance ceremony, open to men only based on the conservative Gulf state's traditions, would continue through Wednesday morning, according to a palace statement.

Qatari newspapers, which devoted their front pages to Tuesday's event, are committed Wednesday to the highly profitable ritual of publishing congratulatory statements from the country's top personalities and tribal dignitaries.