The Greek managers of a Liberian-flagged oil tanker reported missing earlier this month off the coast of Angola in western Africa said Monday they had re-established contact with the vessel and that the ship had been attacked by pirates.

An Angolan official, however, cast doubt on the piracy claim, saying fears of an attack had proved unfounded.

Dynacom Tankers Management said pirates had stolen a large amount of cargo from the Kerala, with which the company had lost contact on Jan. 18 from an anchorage in Luanda. It said it had re-established contact with the ship on Sunday. One crew member was wounded but all were alive and accounted for, it said, adding that "all have clearly been affected by their ordeal." The company did not say how many crew were on board and refused to provide any further details.

Dynacom thanked "European, North American and other international intelligence agencies" for their help and said that representatives of international law enforcement and intelligence agencies were to board the ship to "gather intelligence and forensic evidence."

On Sunday, however, Angolan Navy spokesman Augusto Lourenco was quoted by public broadcaster Radio Nacional de Angola as saying the apparent hijack was a deception and the tanker had been found in Nigeria.

"The ship was waiting for authorization to offload 60 tons of diesel in the port of Luanda," Lourenco said, according to RNA. "On the 18th (of January), a tugboat approached it, made contact with the ship which raised anchor, and they both headed to Nigeria."

"Our concern that it was an act of piracy proved unfounded. It's no more than a simulation by the crew of the tanker and the tug's agent," RNA quoted Lourenco as saying.

It was not possible to immediately reconcile the two accounts.  Pirate attacks so far south along Africa's west coast are highly unusual, and would raise concerns that pirates are expanding their regional reach.