Conflict-weary Somalia was admitted on Friday into the East African Community (EAC) as the eighth member of the bloc as it seeks to expand free trade across the region.
The accession of the fragile Horn of Africa nation, which has a population of 17 million, will boost the EAC market to more than 300 million people.
"We have decided to admit the Federal Republic of Somalia under the treaty of accession," outgoing EAC chair, Burundian President Evariste Ndayishimiye, said at a summit of the grouping in Tanzania.
Somalia -- whose President Hassan Sheikh Mohamud was at the summit -- joins Burundi, the Democratic Republic of Congo, Kenya, Rwanda, South Sudan, Tanzania and Uganda.
Mohamud described joining the EAC as a "new chapter" in the history of Somalia, which also boasts the longest coastline of a mainland African country at over 3,000 kilometres (1,800 miles).
"This moment is not just a culmination of aspiration but a beacon of hope for a future replete with possibilities and opportunities," he told the summit.
The EAC, headquartered in the Tanzanian town of Arusha where the summit was taking place, was founded in 2000 and works to encourage trade by removing customs duties between member states.
It established a common market in 2010.
- 'Pivotal leap' -
Not including Somalia, combined EAC countries covered a land area of 4.8 million square kilometres (1.8 million square miles) and had a combined gross domestic product of $305 billion, according to the bloc's website.
Total EAC trade was $78.75 billion in 2022, it said.
The admission of Somalia could portend more security challenges for the bloc as the country is struggling to stem a deadly insurgency by the Islamist Al-Shabaab group.
After making significant progress, Somalia's offensive against the Al-Qaeda-linked group has stalled for months and raised concerns about the government's capacity to crush the 16-year insurrection.
EAC members Kenya and Uganda contribute troops to an African Union force which was first deployed to Somalia in 2007 to crush Al-Shabaab.
In November last year, the EAC also sent troops into the restive east of the DR Congo, which had joined the bloc last year, after the resurgence of the M23 rebel group.
Mogadishu-based think tank the Heritage Institute for Policy Studies said the accession of Somalia -- which has been seeking to join the bloc since 2012 -- was a "pivotal leap" in the EAC's expansion across East Africa.
But it said in a report ahead of the summit that Somalia's "poor track record in governance, human rights and the rule of law" could hinder its smooth integration into the bloc.
The country has also been embroiled in disputes with its neighbours -- Ethiopia, Djibouti and Kenya -- sometimes leading to a breakdown in diplomatic relations.
However, it has taken steps in recent years to repair regional ties.