Officials from Pakistan, Afghanistan, China and the United States have launched their third round of talks aiming to chart a roadmap for peace negotiations between the Taliban and the government in Kabul.

Saturday's talks, held in the Pakistani capital of Islamabad, are part of the latest effort to finalise a peace plan in Afghanistan, emphasising the need for a direct dialogue between the two sides.

READ MORE: Afghanistan peace talks held in Pakistan

"We are confident that the process would lead to a significant reduction in violence (in Afghanistan)," said Sartaj Aziz, the Pakistani prime minister's foreign affairs adviser.

"We have to exert all our efforts and energies for keeping the process on track."

Preconditions to negotiations

Peace efforts broke down in July after it became known the Taliban leader Mullah Omar, who sanctioned the talks, had been dead for two years.

The announcement led the Taliban to pull out of the talks after just one meeting hosted by Islamabad.

Last month, representatives of the Afghan Taliban said they will participate in the ongoing peace talks only if their conditions, which include the removal of their members from a UN blacklist, are met.

"Some preliminary steps should be taken prior to starting peace because without that, progress towards peace is not feasible," the Taliban said in a statement after an unofficial two-day meeting with people close to the Afghan government was held in Qatar's capital Doha.

The conditions as set by the Taliban included the "establishment of official venue for the Islamic Emirate; removal of blacklist and prize list; release of prisoners and ending poisonous propaganda".

Individuals on the UN blacklist are subject to asset freeze, travel and arms bans.

READ MORE: Afghan Taliban want UN sanctions removed

Yet, at the start of the quadrilateral meetings on Saturday, Pakistan's Aziz said there should be no preconditions to negotiations.

Some observers were also skeptical those demands would be met and there have also been doubts about whether competing factions of the Taliban that have been fighting for control of the movement will be willing to join.

Nevertheless, the Afghan government has said it expects at least parts of the Taliban to agree to peace talks within six months, Chief Executive Abdullah Abdullah told the Reuters news agency in New Delhi last week.

"There might be groups among the Taliban who might be willing to talk and give up violence," Abdullah said, declining to give further details.

He added the countries involved in the four-way talks were discussing where to hold Afghan-led peace talks once some Taliban groups decide to come to the table, and how to address the problem of the groups who do not.

The nearly 15-year conflict has killed thousands of people and profoundly strained the country's economy.