India’s huge wave of Covid-19 infections has hit the international shipping industry, which relies on the country for seafarers, as crews come down with the disease and ports deny entry to vessels.

Ports including Singapore and Fujairah in the United Arab Emirates have barred ships from changing crew members who have recently travelled from India, notices from maritime authorities show. Zhoushan in China has banned the entry of ships or crew that have visited India or Bangladesh in the past three months, according to Wilhelmsen Ship Management, a crew provider.

Industry executives also said that crews coming from India were testing positive for Covid-19 on ships, despite quarantining and testing negative before boarding.

“Earlier we had ships that were infected with one or two people,” said Rajesh Unni, chief executive of Singapore-based Synergy Marine Group, which provides ship crew. “Today, we have a scenario where whole ships are being infected very quickly . . . which means the ships themselves are immobilised.”

India on Thursday reported more than 410,000 Covid-19 infections and almost 4,000 deaths over the previous day. A surge in cases has broken global records and overwhelmed health systems.

South Africa’s port authority said a vessel that arrived in Durban from India this week was quarantined after 14 Filipino crew tested positive for Covid-19. The ship’s chief engineer died of a heart attack.

Along with the Philippines and China, India is one of the world’s largest sources of sea crew. About 240,000 of an estimated 1.6m seafarers globally are from the country, according to International Chamber of Shipping, an industry body

Singapore, a big shipping hub, has widened its ban to cover crew from countries including Pakistan and Bangladesh.

Executives warned the restrictions could send shockwaves through the stretched shipping industry, which transports 80 per cent of global trade, according to UN data.

March’s Suez Canal blockage “will be nothing compared to the [supply chain] disruption coming from being unable to change crews”, said Mark O’Neil, president of InterManager, which represents the crew management industry.

Last summer, about 400,000 seafarers were stranded at sea beyond their contract length because of the pandemic. While that number has fallen, fears are growing due to the global surge in coronavirus cases since March.

“If the travel restrictions continue as they are, we could once again be in a similar situation to the global crew change crisis that we saw in 2020,” said Niels Bruus, head of marine human resources at Maersk, the world’s largest container shipping company.

“The situation has gone from bad to worse when it comes to crew changes. And that’s an understatement,” said Carl Schou, chief executive of Wilhelmsen, which sources 15 per cent of its approximately 10,000 workers from India.

The Norwegian-owned company stopped crew changes in India from April 24 until at least the end of May. Schou added that Covid-19 test results for Indian sailors were not coming through in time for their scheduled departures since “the whole health system has basically collapsed in India”.

Bernhard Schulte Shipmanagement, a German crew management group, said it was temporarily drafting in seafarers from other nations to replace Indians disembarking or scheduled to board ships.

Shipping executives said that seafarers needed to be prioritised in the global vaccination rollout as countries introduce inoculation requirements to enter. But they have been frustrated by the slow pace of efforts to secure jabs through the International Maritime Organization, the UN body responsible for shipping.

“We’re simply tearing our hair out with the bureaucracy and political ping-pong going over this issue of vaccinations,” said O’Neil.

Abdulgani Serang, general secretary of the National Union of Seafarers of India, said he felt authorities had not done enough to get Indian sailors vaccinated: “We failed them.”

Additional reporting by Jyotsna Singh in New Delhi