They reportedly include senior staff of the Indonesian chemical company Indorama and members of their families seized at a residential compound.
The reported release comes days after ex-militia leader Mujahid Dokubo-Asari was released on bail on health grounds.
His arrest for treason in 2005 saw a surge in violence.
Both security and company sources confirmed the hostages' release and it is believed they were handed over to their employer, Eleme Petrochemicals, which is owned by Indorama.
Twelve foreign hostages - five Americans, three Britons, two Indians, a Filipino and a South African - were freed by oil gunmen last week.
Last Mod: 16 Haziran 2007, 18:47