At least nine Nato soldiers have been killed in separate incidents in southern Afghanistan, military officials have said.

Four troops - three Australians and an American - were killed in a helicopter crash in southern Kandahar province - the single worst loss of life for the Australian military in the nearly nine-year Afghan war.

The Nato-led International Security Assistance Force (Isaf) said in a statement on Monday that there was no evidence of "enemy involvement" in the helicopter crash, that also left two soldiers critically wounded.

A Taliban spokesman, however, told Al Jazeera that they shot down the helicopter in Kandahar where there has been "very heavy fighting in recent days".

Five more troops, including four American soldiers, were killed in separate attacks in the country.

Also on Monday, London announced that 300 British troops had now died in Afghanistan after a soldier died from wounds suffered in an explosion earlier this month in the southern province of Helmand.

Deadliest month

The latest death toll has made June one of the deadliest months for foreign troops in Afghanistan.

According to James Bays, Al Jazeera's correspondent in Kabul, more than 60 Nato troops have died this month, making it the deadliest June in the last nine-and-a-half years since international forces have been in the country.

"In fact every single month this year has had a higher death toll than last year - and last year saw more international troops die than any other year in Afghanistan," he said.

The deadliest month for the Western coalition was August last year, when 77 foreign soldiers were killed. Last year, 520 Nato troops died - their deadliest annual total yet.

Australia is the largest contributor - among non-Nato members - to the Isaf alliance, with 1,550 troops currently deployed in the southern province of Uruzgan.

The latest casualties come at a time when a joint Afghan-Nato military operation aimed at rooting out Taliban fighters from their heartland is set to begin in Kandahar.