The Somali insurgent group Hizbul Islam has seized control of Harardheere, a pirate stronghold on Somalia's eastern coast.
Witnesses say insurgents driving at least 10 armed vehicles entered Harardheere without a fight Sunday, after pirates fled the town.
Men who describe themselves as pirates say Hizbul Islam sent agents to the town on Friday, demanding a cut of the pirates' business.
They say pirate leaders had ignored the request, prompting Hizbul Islam to send in its fighters.
There was no immediate word on the fate of hijacked ships that had been anchored off Harardheere.
Somali pirates have made tens of millions of dollars seizing ships for ransom over the last few years. The pirates are currently believed to be holding 24 ships in all, with about 400 crew members.
Some of the ships are anchored off Hobyo, another pirate haven to the north. Witnesses say pirates from Harardheere may have fled there ahead of the Hizbul takeover.
Hizbul and fellow insurgent group al-Shabab have been fighting the fragile Somali government for three years. The groups control large parts of southern and central Somalia and portions of the capital, Mogadishu.
The two Islamist groups were once allies but broke apart last year in a dispute over another port town, Kismayo.
Some information for this report was provided by AP and Reuters.