The latest death, a soldier who died in an attack in eastern Afghanistan, was announced by Nato's International Security Assistance Force [ISAF] on Tuesday.
Just two months ago, in April, the number of foreign soldiers who died in the country was 20, according to the independent icasualties.org website.
The previous deadliest month the allied forces suffered was August last year, when 77 soldiers were killed.
In total, 322 foreign soldiers have died so far this year, compared with a toll for all 2009 of 520.
Western leaders and military commanders concede the escalating death toll of foreign soldiers, most of them American, is attributable in part to intensified military operations against the Taliban in their southern strongholds.
"It's a tough time we're in," General Josef Blotz, a spokesman for ISAF, said.
"We are in the arena, there's no way out now, we have to stay on, we have to fight this campaign," he said this week.
The US and Nato have 140,000 troops in Afghanistan, but that number is due to peak at 150,000 by August on orders by Barack Obama, the US president, as part of a counter-insurgency strategy to speed up the end of the war.
Earlier this year about 15,000 US, Nato and Afghan troops launched an operation in Marjah, the Taliban controlled region of southern Helmand province, as part of a massive operation aimed at flushing out Taliban fighters in what commanders said was the biggest military push since 2001.
However, fighting continues more than four months later, and an even bigger strike in the neighbouring Taliban heartland of Kandahar province, has been postponed.