Logistics company Medserv, which serves the offshore oil and gas industry, said it had suspended operations at its Libyan base at Misrata's port.
"The port is intact -- there does not seem to be trouble in the port and it has not been damaged so far. It is 10 km away from the center of where the trouble is," Anthony Diacono, Medserv's Malta-based chairman, told Reuters.
"All our warehouses are still secure because our Libyan staff still monitor the situation."
Gaddafi's tanks shelled the rebel-held city of Misrata and casualties included four children killed when their car was hit, residents said, adding the death toll for Monday had reached 40.
Reports from Misrata -- Libya's third-biggest city which lies about 200 km (130 miles) east of the capital Tripoli -- could not be verified because Libyan authorities have prevented journalists reaching the city.
Medserv's base in Libya is a joint venture with the Misrata Free Zone Authority.
Diacono said it was unclear who was in control of Misrata's port, which handles general cargo. "It is very hard to get information," he said. "Our operations are not functioning."
With anti-Gaddafi rebels struggling to create a command structure that can capitalize on the air strikes against Libyan tanks and air defenses, Western nations have still to decide who will take over command once Washington pulls back in a few days.
Foreign companies have evacuated workers from Libya and oil shipments from Africa's third-largest producer have come to a virtual standstill.
Diacono said its main Malta base was experiencing a pick up in business due to the turmoil in Libya.
"Companies had equipment heading toward Libya for projects just about come to online -- there are some major projects offshore Libya. These have to be sourced from somewhere," he said.
"Our clients know we have a base in Malta and they have re-routed here and we are picking the slack up."
Medserv's clients include Italian oil group Eni, U.S. Exxon Mobil Brazil's Petrobas and Russia's Gazprom.
Diacono said Medserv was complying with sanctions, adding that they expected to resume operations in Libya at some stage.Western countries, the European Union, Japan, South Africa and United Nations have all imposed sanctions on Libya and frozen government assets.
"We will resume because we are in a sector where the product is needed by both Libya and the rest of the world," he said.
"When things settle down, we are pretty confident that business will pick up again the question we don't know is when - it's matter of time."