The Bangladesh government continued its efforts to send thousands more Myanmar Rohingya Muslim refugees to an isolated island in the Bay of Bengal despite safety concerns raised by the International Red Cross, as the cyclone season looms on the horizon.

With the Bangladesh navy putting the finishing touches to a 5.75 meters (19 feet) high storm wall around Bhashan Char, authorities have delayed the departure of 4,200 of the Muslim-minority Rohingyas to the island this week because of bad weather.

Bangladesh has been praised for the way it has welcomed 1 million Rohingya who have fled military crackdowns in Myanmar into camps along the border in recent years.

However, the government has faced doubts about its plan to send 100,000 Rohingya to the 53-square-kilometer silt island that did not exist two decades ago.

The Bay of Bengal cyclone season starts in days and the International Federation of Red Cross and Red Crescent Societies (IFRC) expressed concerns after a team of experts went to the island.

Up to 20 major storms hit the region each year and 700,000 people have been killed in cyclones in Bangladesh in the past five decades.

“With the cyclone season fast approaching, people on Bhashan Char could become stranded with a shortage of food when major storms strike,” said Sanjeev Kafley, head of the IFRC delegation in Bangladesh.

Kafley said any storm could cut the sea passage to Bhashan Char, “in turn denying the delivery of relief, medicines and other vital supplies.”

The IFRC said its mission found improved infrastructure on the windswept island but called for “urgent investment” to bolster protection for women and children as well as food supplies, health care and schooling.

In the past year, 14,000 Rohingya have moved there and residential buildings, cyclone shelters, food silos, medical facilities and jetties have been built.

About 4,200 are being transferred from the border camps to Chittagong port this week to be sent to Bhashan Char. Heavy seas have delayed their trip to the island, however.

Officials insist Bhashan Char can resist any battering from winds and sea. Navy engineers are increasing an existing nine-foot (three-metre) high storm wall to 19 feet.

“We have finished 43% of the reinforced dam,” project director Commodore Rashed Sattar told Agence France-Presse (AFP).

Sattar said there are three months’ supplies of food and other necessities. “We are completely prepared to face any untoward event. We also have helipads, therefore air cargo is possible if needed,” he said.

Many refugees on Bhashan Char are worried about facing their first cyclone. “We thank the Bangladesh authorities for everything but nobody can control nature. If something goes wrong, we will be in deep trouble,” said Iqbal, a refugee who only gave one name.

Serazul Islam, another island resident, was unconcerned however, “Over 15,000 construction workers have been living here for the past four years. If they are unharmed, I don’t see why we should worry.”