Taliban leader Mullah Mohammad Omar has backed peace talks with the Afghan government, a week after milestone meetings between the two sides in Pakistan.

The message represented the first word in the name of Mullah Omar on the budding peace process that has deeply split the Afghan insurgents' leadership.

Issued ahead of the Muslim holiday of Eid al-Fitr, the message said the Taliban had a legal right to meet Afghan and foreign officials, as long as Islamic ideals were respected in the process.

"Peaceful interactions with the enemies is not prohibited" under Islamic tradition, said the statement published on a website linked to the Taliban.

"The objective behind our political endeavours ... is to bring an end to the occupation."

The Taliban have been fighting since their overthrow in 2001 to expel US-led foreign forces and the US-backed government in Kabul.

Most foreign troops left last year but at least 13,000 remain, most of them training Afghan forces.

Afghanistan and Pakistan said last week's talks were the first official meeting between representatives and that all parties had agreed to start a process.

The Taliban's leadership, however, is known to be divided on the issue, with political chief Akhtar Mohammad Mansour - who frequently speaks for Mullah Omar - in favour of negotiation and top battlefield commander Abdul Qayum Zakir against them.

Mullah Omar, who headed the Taliban's hardline Islamist rule over Afghanistan for five years, has not been seen in public since the US-led intervention in 2001.

Some disgruntled Taliban factions have suggested he is either dead or very ill and others may be making statements in his name.

The new statement did not include audio or a video.

In April, the Taliban published a 5,000 word biography that said their chief was alive, well and in regular contact with the world.

Despite efforts to reassure Taliban commanders, some of their fighters have defected to Islamic State (IS), led by the charismatic Abu Bakr al-Baghdadi.

The new statement made reference to IS, saying: "We have...directed all our mujahideen to preserve their unity and forcefully prevent all those elements who attempt to create differences."