A freight vessel as seen from the seafront of Thessaloniki city anchored at Thermaikos Gulf, Aegean Sea in Greece on April 7, 2020.

There could be "terrible accidents" at sea if shipping crew changes continue to be blocked by coronavirus restrictions, the International Chamber of Shipping (ICS) told CNBC this week.

Of 1.2 million crew members at sea at any one time, around 100,000 usually leave their ships every month to comply with international maritime regulations protecting their health, safety and welfare, according to a joint statement by ICS and the International Air Transport Association.

However, these crew changes have been hindered amid the coronavirus pandemic that has killed nearly 145,000 people and sickened more than 2.15 million worldwide.

"The issue of seafarers and their well-being is crucial, and if this problem is allowed go on for too long, you will find stress levels and health issues, and eventually there will be some terrible accidents," said Esben Poulsson, chairman of the ICS.

Due to government-imposed travel restrictions, flights for seafarers to head home or to travel to ports are now unavailable, while immigration and health screening protocols are also impeding the "vitally necessary crew changes," the statement said.