Streets were shut down to traffic in Mogadishu, which regularly faces attacks from the Islamist al Shabaab militants, for the one-day meeting of IGAD, a grouping that includes Kenya, Ethiopia, Uganda, Djibouti, Sudan, Uganda and Somalia.

The regional leaders discussed Somalia's upcoming vote for a new parliament and president, as well the situation in South Sudan, where fighting in July has further destabilized the five-year-old nation.

The presidents of Kenya, Uganda and Djibouti, and the prime minister of Ethiopia, were in Mogadishu for the summit meeting of IGAD, or the Intergovernmental Authority on Development, officials said.

"It symbolizes the reconstruction of Somalia and Somalia coming back to the (family of) nations," Foreign Minister Abdusalam Omer told Reuters as heads of state flew in. "It signifies that we are defeating international terrorism."

Somalia has hosted visits of individual heads of state, but Omer said this was the first summit gathering for about four decades, since the rule of President Siad Barre, whose toppling in 1991 was followed by two decades of conflict.

Ethiopian Prime Minister Hailemariam Desalegn, chair of IGAD, said Somalia had made progress but more was needed. "IGAD is confident that its efforts will succeed in the complete restoration of peace and stability," he said, according to statements released after the meeting.

Many senior visitors to Mogadishu stay in the airport area, a compound surrounded by high blast walls with barbed wire and patrolled by the African Union AMISOM force. Tuesday's summit was held just outside the perimeter at a nearby hotel.

"The presence of the heads of state in Somalia is a clear dividend of returning stability in the country," AMISOM said in a statement.

Ordinary Somalis were forced to walk around the capital as traffic was blocked from many streets. Al Shabaab has often used vehicles packed with explosives to launch attacks on sites in Mogadishu, blowing up security posts so fighters can storm in.

Mogadishu still bears the scars of war, with many buildings little more than bombed out shells. But there has been a construction boom in recent years, that has seen new buildings erected, often financed by Somalis returning from abroad.

Al Shabaab, which once ruled most of Somalia, has been waging an insurgency to topple the Western-backed government of President Hassan Sheikh Mohamud, who seeks re-election later this year.

Security concerns mean that only a fraction of Somalia's 11 million people will vote in the election, with 14,000 people gathered from the federal states choosing the 275 members of parliament, before the lawmakers then pick the president.

But that is still an improvement on the 135 elders who chose parliament in 2012, and which in turn picked Mohamud.

(Writing and additional reporting by Edmund Blair; Editing by Alison Williams)