(Reuters) - Plans by the German operator of a portion of the Venezuelan state oil company’s tanker fleet to return 10 vessels because of unpaid fees prompted a unit of state-run PDVSA on Tuesday to declare a maritime emergency, according to a document from the state-run firm and sources.

The corporate logo of state oil company PDVSA is seen on a tank at an oil facility in Lagunillas, Venezuela January 29, 2019. REUTERS/Isaac Urrutia

PDVSA’s weak finances, the result of mismanagement, a sharp decline in oil output and U.S. sanctions designed to oust President Nicolas Maduro, have prompted dozens of suppliers and partners to stop working for the company.

The United States and more three dozen other countries have thrown their support behind an interim government being formed by the country’s congress chief, Juan Guaido.

PDVSA’s maritime arm, PDV Marina, lacks about 160 people, including captains, machinists and operators, to immediately take back the 10 vessels from Bernhard Schulte Shipmanagement (BSM), according to a notification by PDV Marina’s security department that was viewed by Reuters.

BSM officially notified PDV Marina’s top authorities of its “unilateral decision to deliver the fleet operated by the company due to lack of payment and cash flow for paying pending salaries and staff onboard,” putting PDVSA in a “critical situation to receive the tanker fleet,” the document said.

PDVSA did not respond to a request for comment. A BSM representative was not immediately available to comment after working hours.

BSM last month confirmed its crews would abandon PDVSA vessels Rio Arauca and Parnaso, held in Portugal due to unpaid fees to several companies. A third vessel operated by BSM, the Icaro, was seized in Curacao by a group of shipping companies claiming unpaid bills from PDVSA.

BSM operated a fleet of 13 tankers owned by PDVSA and two very large crude carriers jointly owned by PDVSA and China’s PetroChina. The amount owed by PDV Marina to BSM is at least $15 million, according to a source at the company and a document seen by Reuters.

Over a dozen tankers with Venezuelan oil around the world have been arrested in recent years by authorities or otherwise prevented from leaving because PDVSA has not paid for services.

The two tankers retained in Portugal arrived in 2017 for repairs and were caught in the middle of legal fights between PDVSA and creditors.

In Curacao, a PDVSA operated refinery got a court order to free the seized tanker Icaro and place its oil in storage until the dispute is resolved. The vessel remains anchored in Curacao waters, according to Refinitiv Eikon vessel data.