Former Soviet leader Mikhail Gorbachev who ended the USSR'S decade-long war in Afghanistan in 1989, on Tuesday warned against repeating the mistakes of the US invasion of the country.

"From the very start (the US invasion) was a bad idea, although Russia initially supported it," Gorbachev told the RIA Novosti news agency.

"Failure should have been admitted earlier," 90-year-old Gorbachev said.

"Now it is important to learn from the situation and at least not repeat such mistakes," he added.

Taliban militants on Sunday completed a military takeover of Afghanistan with little resistance, capitalising on the withdrawal of US-led troops from the country.

The US military had been present in Afghanistan since 2001 when it invaded following the Taliban's refusal to hand over Al-Qaeda's leader Osama bin Laden in the wake of the September 11 attacks.

The Soviet Union had also invaded Afghanistan in 1979 to support an Afghan communist government that was in conflict with Muslim guerrilla fighters.

Shortly after coming to power in 1985, Gorbachev decided to end the Soviet presence in Afghanistan.

Moscow's decade-long war in Afghanistan killed up to two million Afghans, forced seven million more from their homes and led to the deaths of more than 14,000 Soviet troops.

Fighters from the anti-Soviet Mujahideen helped found the Taliban in the early 1990s.