At least 318 US and NATO soldiers have been killed in the first six months of 2010 in Afghanistan, compared to 157 killed in through June 2009, according a website that tracks war casualties, DPA reported.
This month alone, 98 NATO troops have been killed, making it the deadliest month for the US-led international forces since they ousted the Taliban regime in late 2001, according to ICasualties.org.
Four Norwegian, two US, one British and three unidentified NATO soldiers were killed in separate attacks on Sunday, according to the military.
The rise in casualties is due to an increased number of operations conducted by troops as well as heavy Taliban use of roadside bombs that have been the deadliest threat for foreign forces.
Roadside bombings increased by 94 per cent in the first four months of this year compared to the same period in 2009, according to the United Nations.
More than 190 of the troops killed this year were from the United States, while 63 British soldiers and around 60 troops from other nations died in the war, according to the website.
There are currently more than 130,000 international forces in the country, but the total number of foreign troops is set to peak at 150,000 by August, more than two-thirds of them from the US.
Following the deaths of 521 soldiers in 2009, NATO and US officials have been warning of a "tough fight" this year.
The combined forces are planning a major operation in the southern province of Kandahar, the Taliban birthplace and spiritual home, and have already deployed soldiers to areas controlled by the insurgents.
A total of 1,883 foreign soldiers, including 1,139 US and 308 British troops, have been killed in Afghanistan since 2001.