BEIJING - Five Chinese workers abducted earlier this month in Nigeria described their experience as "hell on earth" after arriving in Beijing following their 13-day ordeal, state media reported on Tuesday.

The five were freed in Nigeria's oil-producing delta after gunmen broke into the rented apartment on a construction site where the five were staying and forced them away at gunpoint before dawn on January 5.

The telecom workers, all from the southwestern province of Sichuan, were first taken to a tiny islet in a swamp and then moved to a larger island where they were held until their release last week.

The men had been sleeping at the time of their abduction and four of the five were wearing only their underwear.

"Their only protection on the mosquito-infested island was dirty jackets given to them by the bandits," the report said, adding the men were covered in bites.

Thousands of foreign oil workers have left Nigeria in the past year as attacks and kidnappings have multiplied and as lawlessness grows in the Niger Delta region.

The release of the hostages, who were in good health, followed negotiations by a team that included Chinese embassy staff and officers from the Sichuan Telecommunication Company, the mens' employer, the report said.

It made no mention of the deal to secure their release or whether any ransom was paid.

Two of the five were interpreters from the Sichuan capital of Chengdu, while the other three were technicians from the provincial cities of Meishan and Neijiang.