Bangladesh went into a strict Covid-19 lockdown on Thursday, with the army and police ordered to stop people leaving their homes except for emergencies or to buy essentials.

The government says the South Asian nation of 168 million people is seeing an "alarming and dangerous" rise in cases, blamed largely on the highly infectious Delta variant.

Hospitals are struggling, particularly in areas bordering India where the strain was first detected. Some rural towns have recorded infection rates of 70 percent.

The shutdown announcement last week has sparked an exodus of migrant workers from Dhaka, with thousands cramming onto dangerously packed ferries.

Dhaka's police chief told reporters that from Thursday anyone leaving home without a good reason would be fined and may face arrest.

"If we need to file 5,000 cases and arrests a day, we will," Shafiqul Islam told a press conference.

- 'People are dying' -

The government has ordered the army and border police be deployed. All offices and shops will be shut with only local food markets allowed to open for a few hours a day.

"We are hopeful these tough measures will work. We have to contain the virus at any cost," health department spokesman Robed Amin told AFP.

But Sagar, an 18-year-old street food seller in Dhaka, was angry.

"The government is imposing the lockdown only to kill the poor. There will be no work for us, no help from anyone," he told AFP.

Excluded from the lockdown are garment factories supplying Western giants such as H&M and Walmart. The sector is a key exporter but faces stiff competition from China and Vietnam.

Touhidul Islam Chowdhury, who owns a small loan recovery firm, said the shutdown should be "enforced harshly".

"A lot of people are dying and getting infected," he told AFP. "The army should have deployed much earlier."

- Vaccines -

Bangladesh has reported nearly 900,000 infections and just over 14,500 virus deaths, but experts say the actual toll could be much higher due to underreporting.

More than two-thirds of new virus cases in Dhaka are of the Delta variant, according to a recent study by the independent Dhaka-based International Centre for Diarrhoeal Disease Research.

Health authorities have said they will resume the country's inoculation drive from Thursday.

The first phase ground to a halt when India stopped exporting AstraZeneca vaccines earlier this year to focus on its own needs.

Bangladesh is expected to receive this weekend the first shipment of 2.5 million Moderna vaccines promised by the United States.

A Chinese embassy official has said Beijing is also sending about two million Sinopharm vaccines doses that Dhaka bought, adding to 1.1 million shots already donated by China.