Indian authorities sought military help in two districts of northern Uttar Pradesh state after heavy rains left hundreds of villages marooned.
Most of the victims are children, an official from Department of Disaster Management says
A Red Cross official told AFP meanwhile that smaller mudslides had occurred since Monday in eastern Freetown and in Sierra Leone's second city of Bo, with the rainy season far from over.
But as officials spoke of entire communities washed away in mudslides, rescue efforts were hampered by a lack of equipment and the challenges posed the search and excavation work.
Health Ministry warns about water-borne diseases following floods caused by heavy monsoon rains over weekend
Heavy rains have hit more than a dozen districts in the country's far eastern region as well as some areas in the west since Friday morning, the home ministry said.
"So far 11 people have died in this accident -- eight of them in Khorasan Razavi, two in Golestan and another in North Khorasan," Red Crescent rescue chief Morteza Salimi told the ISNA news agency.
Since the start of August, flash floods have caused widespread destruction in the provinces of Dien Bien, Yen Bai, Son La, Cao Bang and Lai Chau, the Hanoi-based disaster control office said in a statement.
Alrosa, Russia's largest diamond producer, said in a statement on its website that water had broken through into the mine at around 4:30 pm (0730 GMT), while there were "more than 100 people" inside.
Flash floods have disrupted air travel, inundated rail tracks and swallowed farmland across the rice-farming region of Isaan, affecting more than one million Thais.
The victims were working in fields in Odisha state when lightning bolts struck them, the state's top disaster management official said. Fifteen people were injured on top of the 11 dead.
At least 25,000 students affected as floods force closure of 200 schools
Images shared on social media and Turkish television showed huge hailstones battering the streets of Turkey's most populated city and cars submerged in the torrential downpour.
25 of 37 villages under water in Cotabato after three weeks of heavy rains
"They seem to have drowned in the floodwaters. The bodies were found buried in muck," A B Parmar, a police inspector at the scene, told AFP, adding the deceased were from the same family.
With scores now dead in monsoon floods across the country, Prime Minister Narendra Modi was to fly over Gujarat later Tuesday to inspect the devastation, officials said.
Dramatic footage circulating on social media showed the riverside pagoda sinking into the flood waters in Magway region, with shocked bystanders looking on as its golden spire collapsed beneath the waves.
Driving winds, rain bring flash flooding to Turkey's largest city, disrupting transport for millions
More than 110,000 people evacuated as central and eastern parts of Jilin province 'inundated', Xinhua reports
Turkey's Foreign Ministry expresses condolences to India over losses of life due to unprecedented rain damage
Heavy seasonal rains last week caused severe flooding that tore up roads and destroyed houses on Japan's southernmost island of Kyushu, with hundreds of thousands of people forced to flee their homes.