The Taliban were quick to dismiss reports of the truce minutes after Karzai made the announcement on Facebook, saying the former president appeared to be referring to a message about last year's Eid holiday ceasefire.

"It is hoped that media and social media users do not become victims of (this) mistake," said Taliban spokesman Zabihullah Mujahid.

Many Afghans -- exhausted by decades of war and violence -- have pinned their hopes on another truce for the next week's Eid holiday, marking the end of Ramadan.

Karzai's announcement unleashed a brief spell of confusion across the country, with media outlets firing off tweets and breaking news reports announcing the alleged truce.

"Former Afghan president shame on you for posting baseless news," wrote Facebook user Amanullah Kamran.

"You are making fun of yourself by posting fabricated news," added Anwar Taskin.

Karzai's team later acknowledged the mistake.

"We sent the statement based on the audio clip that had been published... by the Taliban. And, we were told that the clip is from today," said Karzai spokesman Yusof Saha.

The gaffe comes just hours after Karzai along with several other Afghan opposition figures concluded two days of talks with top leaders from the Taliban movement in Moscow.

In a joint statement after the meeting, the parties said they'd had "productive and constructive" discussions focusing on several issues but stopped short of announcing a new ceasefire deal.

The Taliban have baulked at repeated US calls to reduce violence while negotiations between the insurgents and Washington are ongoing.

Last June, the Taliban observed an unprecedented ceasefire with Afghan forces during the Eid holidays sparking hopes that the war could be resolved through peaceful means.

However, fighting has only intensified in the ensuing months even as the insurgents and Washington have held repeated rounds of talks aimed at ending the nearly 18-year-old war.