Most of the victims in a deadly blaze that engulfed a block housing immigrant workers were from India, Kuwait's foreign minister said on Thursday, raising the death toll to 50.

Three Filipinos were among the dead, Philippines officials said, after the fire sent black smoke billowing through the six-storey building south of Kuwait City.

Most of oil-rich Kuwait's four million-plus population is made up of foreigners, many of them from South and Southeast Asia working in construction and service industries.

Dozens more were injured in the fire in Mangaf, south of Kuwait City, which broke out around dawn on Wednesday at the ground level of the block housing nearly 200 workers.

"One of the injured died" overnight, Foreign Minister Abdullah Al-Yahya told reporters, after 49 people were declared dead on Wednesday.

"The majority of the dead are Indians," he added. "There are other nationalities but I don't remember exactly."

Indian Prime Minister Narendra Modi said the country is "doing everything possible to assist those affected by this gruesome fire tragedy", in a post on X late on Wednesday.

Next of kin will receive payments of 200,000 rupees ($2,400), Modi's office announced.

India's junior foreign minister Kirti Vardhan Singh, who has arrived to help survivors and repatriate remains on an Indian air force plane, said DNA testing was needed to identify some victims.

"Some of the bodies have been charred beyond recognition, so DNA tests (are) underway to identify the victims," he told Indian media.

In Manila, the Department of Migrant Workers said three Filipinos died from smoke inhalation, with two more in critical condition while six escaped unharmed.

"We are in touch with the families of all the affected (workers), including the families of those two in critical condition and the families of the three fatalities," Migrant Workers Secretary Hans Leo J. Cacdac said in a statement.

Kuwaiti officials have detained the building's owner over potential negligence and have warned that any blocks that flout safety rules will be closed.

The blaze was one of the worst seen in Kuwait, which borders Iraq and Saudi Arabia and sits on about seven percent of the world's known oil reserves.

In 2009, 57 people died when a Kuwaiti woman, apparently seeking revenge, set fire to a tent at a wedding party when her husband married a second wife.