Arrested Taliban suspects and confiscated arms and ammunition are shown to the media at a police compound in Ghazni, east of Kabul, Afghanistan, Thursday. (Rahmatullah Naikzad/Associated Press)

Two American troops died in fighting in Afghanistan on Thursday, while NATO and local officials said coalition and Afghan forces killed dozens of insurgents in a series of ground and air engagements.

U.S. Defence Secretary Robert Gates, meanwhile, arrived in the Afghan capital for meetings with President Hamid Karzai and NATO commander Gen. David Petraeus. The Pentagon chief also plans to visit U.S. troops in Afghanistan.

NATO said one U.S. service member was killed in the country's east and the other in the south — regions where fighting between the coalition and Taliban insurgents has been at its most intense. No other details were given in keeping with standard NATO procedure.

The deaths bring to three the number of U.S. service members killed in September and follow a spike in casualties during the last two weeks of August that saw the monthly total rise to 55. The August figure was still below the back-to-back monthly records of 66 in July and 60 in June.

Total U.S. combat deaths for January-August of this year — 316 — exceeded the previous annual record of 304 for the whole of 2009.

NATO said coalition forces beat back an attack on a combat outpost in Paktika province's Barmal district along the mountainous border with Pakistan, killing at least 20 insurgents.

Troops first returned fire with mortars and small arms before calling in an air assault, the alliance said in a statement, adding that no NATO or Afghan government forces were killed.

NATO also said it had killed or wounded as many as 12 insurgents, including two commanders, in an airstrike Thursday on a car travelling along back roads in northwestern Takhar province's Rustaq district.