Lethal bombing attacks in Afghanistan on Tuesday made October the deadliest month for American forces since the war began in 2001, a Pentagon official said.

"US Marines from Fox Company 2nd Battalion 3rd Marines are engulfed in a storm of dust and debris as a CH-53 helicopter lands to transport them from their forward operating base in Farah Province, southern Afghanistan, on October 12. Lethal bombing attacks in Afghanistan on Tuesday made October the deadliest month for American forces since the war began in 2001, a Pentagon official said."

Improvised explosives claimed the lives of eight American soldiers and an Afghan civilian a day after 14 American soldiers and narcotics agents were killed in two separate helicopter crashes.

The deaths brought the number of Americans killed to at least 53 for the month, according to the independent website icasualties.org, compared to 51 killed in August.

A Pentagon official said it was the worst month for American troops since the US-led invasion of Afghanistan in 2001.

Tuesday's deaths raised the number of foreign soldiers killed in Afghanistan so far this year to 445, according to an AFP tally based on icasualties.org. Of those, 277 were Americans.

NATO said the bombings on Tuesday were "multiple complex IED attacks," referring to improvised explosive devices that have become the scourge of NATO-led troops fighting Islamist insurgents.

The IEDs are usually homemade bombs planted by insurgents by roadsides and detonated remotely to specifically target foreign troops on patrol, with insurgents sometimes following up with small arms fire.

"An Army Honor Guard prepares to carry the flag-draped casket of Staff Sgt. Vernon Martin into St. John's Baptist Church for his funeral service on October 19 in Savannah, Georgia. Martin, 25, of Savannah was one of eight US soldiers killed October 3 during a fierce battle at Combat Outpost Keating in Afghanistan."

The Pentagon says the improvised explosives are the single biggest killer of foreign troops in Afghanistan.

The spike in casualties comes as US President Barack Obama faces a fraught decision on whether to send additional American troops to bolster the more than 100,000 NATO-led forces waging war against the Taliban and its allies.

The top commander of US and NATO forces, General Stanley McChrystal, has requested tens of thousands reinforcements, saying more boots on the ground will allow the international force to turn the tide against the Taliban-led insurgency.

The international force includes nearly 68,000 American troops.

Obama said last week that he might make up his mind on the commander's request for 40,000 more troops before the Afghan run-off election on November 7, but might not announce the decision until afterward.