Bangladesh is struggling to contain its worst wave of infections yet.

With Bangladesh under a nationwide lockdown to fight a third wave of the coronavirus, hospitals in the capital, Dhaka, are reaching capacity and demand for oxygen is exceeding supply.

But on Sunday, the government granted an exemption allowing the country’s critical ready-made garments industry to keep operating, prompting fears among experts that the health crisis could worsen as thousands of employees from outlying areas return to the capital to work.

Dhaka’s three main hospitals have run out of intensive-care beds, forcing administrators to turn patients away, Robed Amin, a government health department spokesman, said in an interview. The government has been trying to expand the health system’s capacity but its facilities are becoming overwhelmed, he said.

“If we have 100 hospitals and all the beds are occupied, what can we do?” he said.

A.K.M. Nasiruddin, director of the Dhaka North City Corporation hospital, a dedicated Covid-19 facility, said that all 500 of the hospital’s oxygen-equipped beds were filled with patients. Hospital administrators were rushing to convert the remaining beds so that they could treat intensive-care patients, he said.

Bangladesh, a densely populated country of 160 million, experienced relatively few infections and deaths in its first two waves of the virus compared with other countries in South Asia. Unlike neighboring India, Bangladesh did not run out of oxygen supplies or hospital beds during a second wave this spring, with case numbers tapering off after an April peak.

But last month, Bangladesh recorded more than 5,600 deaths attributed to Covid-19 — more than a quarter of the country’s total since the pandemic began.

After beginning a mass vaccination drive in early July, far later than many other Asian nations, around 4.3 million people were fully vaccinated by Aug. 1, according to government statistics. That is about 4 percent of Bangladesh’s adult population.

Before the Islamic holiday of Eid al-Adha last month, the government eased lockdown restrictions, ignoring health experts’ warnings that increased travel could fuel an outbreak. Asim Kumar Nath, director of Mugda Medical College Hospital in Dhaka, said the Eid decision “made the situation worse for Bangladesh.”