At least 10 Afghan soldiers have been killed in an attack in the southern province of Helmand, local officials say.
The soldiers died when insurgents attacked a security checkpoint in Washir district, the Helmand provincial government said.
Four other soldiers were wounded in the attack on Sunday night, reports said.
Meanwhile an Afghan soldier is reported to have killed two foreign soldiers on Monday in eastern Laghman province.
"Isaf [International Security Assistance Force] soldiers returned fire and killed the attacker," an ISAF spokesman told Agence-France Presse (AFP) news agency.
The incident is one of at least 12 so-called "green on blue" attacks by Afghan security personnel on international troops this month.
A total of 42 Isaf personnel have been killed by members of the Afghan security forces this year.
Currently, approximately 130,000 ("blue") Nato troops are fighting insurgents in Afghanistan alongside 350,000 ("green") Afghans.
'Insider plot'In the Helmand province attack, at least five other soldiers were also reported missing. It is not clear whether they were abducted or went with the attackers voluntarily.
"There was an attack on one of our posts in Washir district. Ten soldiers are dead in that attack," Col Mohammad Ismaiel Hotak, deputy head of the regional co-ordinating body for the Afghan army and the US-led NATO force, was quoted by AFP as saying.
But a spokesman for the Helmand provincial government, Daud Ahmadi, told AFP that the attack was an "insider plot".
"Five others have gone with the Taliban with their guns."
Both officials said that the incident was being investigated.
