Outlawed Kurdish militants Saturday declared a ceasefire with Turkey following a landmark call by jailed PKK leader Abdullah Ocalan asking the group to disband and end more than four decades of armed struggle.

President Recep Tayyip Erdogan, who backed the peace process initiated by a close nationalist ally, warned that Turkey would pursue the anti-PKK fight unless the group kept their pledge to disband.

"In order to pave the way for the implementation of (Ocalan's) call for peace and democratic society, we are declaring a ceasefire effective from today," the PKK executive committee said, quoted by the pro-PKK ANF news agency.

It was the first reaction from the Kurdistan Workers' Party (PKK) after Ocalan this week called for the dissolution of the group and asked it to lay down its arms.

"We agree with the content of the call as it is and we say that we will follow and implement it," said the committee, which is based in northern Iraq.

"None of our forces will take armed action unless attacked," it added.

The PKK is designated a terrorist group by Turkey, the United States and the European Union. It has waged an insurgency since 1984.

The group's original aim was to carve out a homeland for Kurds, who make up about 20% of Turkey's 85 million people.

Recently however, the group has called for more autonomy and cultural and linguistic rights, rather than independence.

Since Ocalan was jailed in 1999 there have been various attempts to end the bloodshed, which has cost more than 40,000 lives.

After several meetings with Ocalan at his island prison, the pro-Kurdish DEM party relayed his appeal Thursday for PKK to lay down its weapons and convene a congress to announce the organization's dissolution.

The PKK said Saturday it was ready to convene a congress but "for this to happen, a suitable secure environment must be created" and Ocalan "must personally direct and lead it for the success of the congress."

The group also said Ocalan's prison conditions must be eased.

He "must be able to live and work in physical freedom and be able to establish unhindered relationships with anyone he wants," said the group.

Hours after the PKK declared a ceasefire, Erdogan warned: "If the promises given are not kept ... we will continue our ongoing operations."

He was speaking from Istanbul at a meal to break the Ramadan fast.

There was nothing, he said, "that would disturb the sacred spirits of our martyrs" killed by the PKK.

Turkey would be the winner, he insisted.

"We always keep our iron fist ready in case the hand we extend is left hanging in the air or bitten," he added, in what appeared to be a warning to the PKK.

Erdogan described Ocalan's appeal Friday as "a historic opportunity."

Analysts say establishing a truce with the PKK would help both Turkey and Syria, where strongman Bashar al-Assad was ousted late last year.

"A peace deal with the PKK is likely to make it easier to reunify and establish a more stable Syria," Anthony Skinner, director of research at Marlow Global, told AFP.

"This is a key objective for the Turkish government, which has had to contend with the ongoing threat of cross-border mass migration and terrorism," he said.

Turkey's army, which has troops deployed in northern Syria, regularly attacks areas controlled by Syrian Kurdish forces that it considers terrorists linked to the PKK.

Analyst Bayram Balci, a Turkish foreign policy expert at the Paris Institute of Political Studies, said the PKK understood the regional context had changed.

Syria's Kurdish fighters "no longer have the support of Assad, they may no longer have the strong support of the Americans," he said.

"The threat of Daesh still exists, but it is not as strong as before. And then there is also a kind of fatigue," he added, referring to the Islamic State terror group.

Iraq has welcomed Ocalan's call as "a positive and important step towards achieving stability in the region."

The PKK's presence in Iraq has been a recurrent source of tension between Baghdad and Ankara.

The group holds positions in Iraq's autonomous Kurdistan region, where Turkey also maintains military bases and often carries out ground and air operations against Kurdish militants.

After the last round of peace talks collapsed in 2015, no further contact was made with the PKK until October when hard-line nationalist MHP leader Devlet Bahceli offered a surprise peace gesture if Ocalan rejected violence.