Jailed Kurdish leader Abdullah Ocalan called on his followers to take a "historic" decision to lay down their arms, according to a statement on Saturday, a crucial step in Turkey's drive to end the rebels' 30-year struggle for greater autonomy.

Turkey's president, Recep Tayyip Erdogan, welcomed the call but said the rebels had failed to deliver on previous pledges.

Ocalan has been serving a life term in prison on an island south of Istanbul since 1999 but retains influence over his fighters. He has been working with Erdogan since 2012 to negotiate a ceasefire.

Sirri Sureyya Onder, a member of parliament from the pro-Kurdish Peoples' Democratic Party (HDP), read a statement from Ocalan that urged the Kurdistan Workers Party (PKK) to attend a planned congress on disarmament.

"I invite the PKK to attend an extraordinary congress in the spring months in order to make the strategic and historic decision to abandon the armed struggle," Onder said, quoting Ocalan. An HDP delegation met with Ocalan this week.

Onder spoke live on television alongside Deputy Prime Minister Yalcin Akdogan, who said the move towards disarmament marked "an important phase” in the resolution process. "We view this statement as important to accelerate the work on disarmament ... and for democratic politics to come to the forefront," Akdogan said.

The statement also attributed to Ocalan a series of 10 measures that Kurds want to ensure peace, including a new constitution. Erdogan is also seeking a new constitution, in an effort to give his office more executive powers and to replace a charter drawn up by technocrats after a 1980 military coup.

The insurgency has claimed more than 40,000 lives, mostly Kurdish, since 1984. In late 2012, Erdogan launched jailhouse talks with Ocalan, who declared a ceasefire in 2013, but the peace process stalled. Many Kurds blamed the impasse on the Turkish government’s failure to follow through on promised reforms, and the PKK will likely wait for signs of progress before agreeing to disarm.

The government, for its part, appeared skeptical that fighters would implement the plan. "Of course calls are good, but what is most important is implementation,” Erdogan said at a news conference. “How much will implementation be reflected in the field ahead of an election?"

Facing a parliamentary election in June, the government said it expected Ocalan to declare an end to the PKK's armed struggle for greater autonomy and cultural rights for Turkey's estimated 15 million Kurds.

The PKK's units have joined other Kurds to battle Islamic State in Syria and Iraq. Kurdish victories, especially in the Syrian town of Kobane, have raised worries in Ankara about an emboldened PKK at the bargaining table.

Less than two weeks ago, the PKK warned the government that negotiations could break down unless it took concrete steps to further the peace process.

"With today's events, a critical point has been reached in Turkey's democratization, the expansion of freedoms and for lasting peace," said HDP chairman Selahattin Demirtas, whose deputies have shuttled from Ocalan's island prison near Istanbul to Qandil mountain in northern Iraq, where the PKK is based.

The disarmament congress would be held after consensus on the 10 measures outlined in the statement is reached, he said. It was not clear who would attend the conference or whether PKK forces outside of Turkey would be expected to lay down arms.

Turkey, the United States and the European Union have designated the PKK as a “terror” organization. The rebels declared a ceasefire in Turkey in 2013, but violence still sporadically erupts.

Al Jazeera and wire services