Pakistani troops have mobilised to help the desperately poor victims of an earthquake centred in nearby Iran that killed at least 34 people, as the United States offered help to both nations.

The epicentre of Tuesday's 7.8 magnitude quake lay in southeast Iran but all of the deaths so far have been reported across the border in Pakistan's remote province of Baluchistan, where hundreds of mud-built homes suffered damage.

The powerful tremor shook the ground and caused panic as far afield as Kuwait and the Indian capital New Delhi. Thousands of people evacuated towering residential and office buildings in Dubai.

In Pakistan, officials said that regular army and paramilitary forces had deployed to help the relief effort after the quake brought down homes in the Mashkail area of Baluchistan.

Two military helicopters carrying medical teams have been sent to the area while paramilitary troops are being mobilised to supplement the relief efforts, they said.

"At least 34 people have been killed and 80 others wounded in Mashkail," a local government official told AFP.

"The bodies are at the hospital and the injured are being treated by army doctors. Paramilitary forces are busy in rescue work."

Baluchistan, a dirt-poor province bordering Iran and Afghanistan, is plagued by Islamist militancy, attacks on the Shiite Muslim minority and a separatist Baluch insurgency.

Putting aside America's longstanding enmity with Iran, and its more recent strains in relations with Pakistan, US Secretary of State John Kerry offered "our deepest condolences" to the families of the dead and to the injured.

"We stand ready to offer assistance in this difficult time," he said.

Disaster relief contributed to an earlier thaw in relations between the United States and Iran, which -- then led by reformist president Mohammad Khatami -- accepted US personnel following the huge Bam earthquake in 2003.

The United States has also engaged in disaster diplomacy with Pakistan, briefly improving its abysmal image in the country through a robust relief operation following a 2005 earthquake in Pakistani-administered Kashmir.

UN chief Ban Ki-moon also expressed condolences after Tuesday's Iran-Pakistan disaster.

"I will continue to follow the news closely as relief workers and search-and-rescue teams reach the areas. The United Nations stands ready to help as necessary if asked to do so," he said.

The quake struck at 3:14 pm Iranian time (1044 GMT) with its epicentre around 80 kilometres (50 miles) east of the city of Khash, in the Iranian province of Sistan Baluchistan, US seismologists said.

A local health official in Iran told the Fars news agency that more than 20 villages were probably "severely damaged", based on initial reports.

At least 27 people were hurt in Iran, according to a local governor speaking to the IRNA news agency, but there was no immediate confirmation of any deaths.

The quake came a week after another struck near Iran's Gulf port city of Bushehr, killing at least 30 people.

The International Atomic Energy Agency reported that the latest quake had caused no damage to Iran's nuclear power plant at Bushehr or any other nuclear facilities.

Iran sits astride several major seismic faults. The Bam quake in December 2003 killed more than 26,000 people and destroyed the city's ancient mud-built citadel.

The 7.6-magnitude earthquake that hit Pakistan in October 2005 killed more than 73,000 people and left about 3.5 million homeless, mainly in Pakistan-controlled Kashmir and parts of northwestern Khyber Pakhtunkhwa.

David Rothery, who chairs the volcanoes, earthquakes and tsunamis course at Britain's Open University, said the depth of Tuesday's quake -- 82 kilometres underground -- would have lessened its impact.

But he added that the area straddling the Iran-Pakistan border "is mountainous, and damage can be expected from landslides as well as because of poorly constructed buildings".

burs-jit/jw