Smiling and dressed in a red windbreaker, the 69-year-old leader walked out on the stage of an Istanbul aviation festival and began to toss out flowers to flag-waving supporters in the crowd.

He arrived together with two close allies, Azerbaijani President Ilham Aliyev, and the contested Libyan prime minister Abdelhamid Dbeibah.

Both countries have fought wars using Turkey's combat drones, which will feature prominently at Teknofest, a major aviation, tech event which kicked off on Thursday at Istanbul's Ataturk Airport.

Erdogan had been lying low since getting sick live on television on Tuesday night.

Turkey's Health Minister Fahrettin Koca has said Erdogan is suffering from gastroenteritis. The digestive problem is easily treated and usually clears up in a few days.

But it has disrupted Erdogan's attempts to seize momentum in the run-up to Turkey's most important election in generations on 14 May.

Millions of Turkish citizens living abroad already began voting Thursday. Some 3,416,098 Turks living abroad are eligible to vote, 277,646 of whom are first-time voters, local media reported.

Erdogan looked healthy on Saturday addressing the crowd with a microphone in his hand, describing government efforts to help the victims of a massive February earthquake that claimed more than 50,000 lives.

But he refrained from addressing his absence or the health scare, instead proclaiming the launch of a new "century of Turkey".

"Hatred and grudges"

Most polls show Erdogan slightly behind his secular rival Kemal Kilicdaroglu in Turkey's most pivotal election of modern times.

His Islamic-rooted party's control of parliament through an alliance with an ultra-nationalist group is also under threat.

Erdogan has a penchant for campaigning and most analysts thought he could reverse the dip in polls on the campaign trail.

He appeared in five cities over two days before getting sick on late-night TV.

Erdogan tried to compensate by appearing at events via video link, launching a nuclear power plant with Russia's Vladimir Putin on Thursday and inaugurating a bridge the next day.

But the events lacked the electric atmosphere that Erdogan often generates when he speaks to adoring crowds at events aired live across the nation of 85 million people.

The rock concert atmosphere of his past campaigns has also been muted by mourning over the death and destruction wrought by the 7.8-magnitude earthquake across swathes of Turkey's southeast.

Erdogan has decided against playing music at his appearances out of respect for the victims.

Broad opposition

He has instead focused on listing his achievements, including the construction of millions of new houses, and his push to resurrect Turkey's military might.

The drones have played a central role in Turkey's projection of power, most recently helping Ukraine fend off Russia's advance on Kyiv at the start of the Kremlin's invasion last year.

But Erdogan is facing the toughest challenge of his rule.

Kilicdaroglu has formed the type of broad-based coalition that Erdogan had mastered in crafting over 20 years.

The opposition alliance includes some of Erdogan's former allies, liberals, Islamists and nationalists, as well as Kurds.

Erdogan returned to his preferred theme on Saturday of portraying opposition members as Western "agents" bent on undermining Turkey.

"With the scandalous statements they have made in recent days, they are revealing their hatred and grudges," Erdogan said of his opponents.

"But no matter what they try to do, nothing will come of it."

*This story was edited by Ahram Online