Thousands of people are defying a nationwide coronavirus lockdown in Bangladesh to see Rani, a 51-centimetre tall cow whose owners claim it is the world's smallest.

The 23-month-old dwarf cow has become a media star with scores of newspapers and television stations throwing the spotlight on the tiny animal at a farm near Dhaka.

Pictures of Rani on social media have set off a tourist frenzy.

Despite a nationwide transport shutdown because of record coronavirus infections and deaths, people are flocking in rickshaws to the farm in Charigram, 30 kilometres south-west of Dhaka.

“I have never seen anything like this in my life. Never,” said Rina Begum, 30, who came from a neighbouring town.

Rani is 66 centimetres long and weighs only 26 kilograms. The owners say it is 10 centimetres shorter than the smallest cow in Guinness World Records.

M.A. Hasan Howlader, manager of Shikor Agro farm, used a tape measure to show dozens of onlookers how Rani dwarfs closest rival Manikyam, a cow in the Indian state Kerala that currently holds the world record.

“People come long distances despite the coronavirus lockdown. Most want to take selfies with Rani,” Mr Howlader told AFP. He said Guinness World Records had promised a decision in three months.

“More than 15,000 people have come to see Rani in the past three days alone,” he said.

“Honestly speaking, we are tired.”

Guinness World Records said Manikyam, from the Vechur breed, was 61 centimetres high in June 2014.

Rani is a Bhutti, or Bhutanese, cow. The breed is prized for its meat in Bangladesh. The other Bhuttis on the farm are twice Rani's size.

“We did not expect such huge interest. We did not think people would leave their homes because of the worsening virus situation. But they have come here in droves,” the manager said.

Sajedul Islam, the government's chief vet for the region, said Rani was a product of “genetic inbreeding” and was unlikely to become any bigger.

Mr Islam said he had told the farm to restrict the influx of tourists.

“I told them they should not allow so many people to crowd the farm. They may carry diseases here that threaten Rani's health,” he said.