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By Austin Ekeinde

PORT HARCOURT, Nigeria, Feb 11 (Reuters) - Unknown gunmen attacked at least two energy industry ships in Nigeria on Monday, killing one sailor on a naval escort vessel, authorities said.

It was the second wave of armed attacks on shipping in Nigeria's busiest oil and gas export hub in two months, and follows a call by the world's shipping union to declare Africa's top oil producer a "war zone".

"There was an attack this morning on a naval escort to an NLNG staff boat from Bonny to Port Harcourt. We lost one rating," said Navy spokesman Henry Babalola.

The Nigeria Liquefied Natural Gas (NLNG) plant located on Bonny Island exports 22 million tonnes per year of frozen, compressed gas to markets in the industrialised world.

It runs a regular boat service for staff to the Rivers state capital Port Harcourt.

Another attack occurred at around the same time on an oil industry ship in the Bonny channel for the French oil company Total <TOTF.PA>, an industry source said.

CREW MEMBER RESCUED

The attackers shot at the bridge, boarded and one crew member fell overboard, but he was rescued by another vessel 30 minutes later and no one died in that incident, he added.

Bonny Island is also home to a 400,000 barrel per day oil export terminal operated by Royal Dutch Shell <RDSa.L>.

In January, Danish shipper A.P. Moller-Maersk suspended all shipping to a major oil industry port near Bonny, Onne, after militants shot at six ships in the Bonny channel.

The International Transport Workers' Federation (ITF), which represents 186 maritime unions and 700,000 seafarers worldwide, said it was pressing the industry to declare Nigerian waters a war zone because of an alarming rise in attacks and kidnappings.

Oil companies have been struggling to cope with a wave of violence in Nigeria's oil heartland, fuelled by widespread poverty, corruption and lawlessness.

The latest round of violence began in early 2006 when a new rebel coalition, the Movement for the Emancipation of the Niger Delta, blew up oil facilities and abducted dozens of foreign workers in a series of raids.

Since the initial onslaught, which cut 20 percent of national oil output, violence has ebbed and flowed and the line between militancy and crime has become blurred. (Reporting by Austin Ekeinde; Writing by Tom Ashby; Editing by Tim Pearce)

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