Growing unrest in Bahrain has led to staff shortages at the island's ports and slower operations although terminals were open, shipping sources said.

Bahrain declared martial law on Tuesday, looking to end weeks of protests by its Shi'ite Muslim majority, with Saudi troops on hand in the Sunni-ruled kingdom to help quell the unrest. "Port operations (in Bahrain) have been at a slow pace for the last two days," a shipping source said. "Some people are not reporting for duty."

Danish shipping and oil A.P. Moller Maersk said its ship container and general cargo terminal, the only one of its kind in Bahrain, had been affected.

"We have faced some issues with staff shortages, which have had some impact on operations, but vessels continue to call and we continue to work them," said a spokesman for its unit APM Terminals. "The port is open as usual."

APM Terminals said there were no security issues at the port.

"We have made no recommendations for expats to leave at this stage, as there have been no announcements of any threats to expats in Bahrain," the spokesman said.

A trade source in the Middle East said he had not heard of any disruption to exports of oil products.

In any case, refined products shipments would be lower because of planned maintenance at the state-run Bahrain Petroleum Co refinery.

A three-month state of emergency in Bahrain will hand considerable powers to security forces.

"Local authorities have cordoned off certain parts of the island creating some transportation difficulties," maritime company Inchape Shipping Services said. (Reuters)