Just weeks after elections, protesters outside Ukraine's parliament are accusing lawmakers of remaining idle and allowing the country to descend into chaos. (Reuters)

Pro-Russian separatists on Wednesday rejected a call to disarm during a cease-fire that Ukraine is preparing to start unilaterally within days.

Ukrainian President Petro Poroshenko said the truce would be the first step of a 14-point plan to end the violence that has engulfed the east of the country for months. Acting defense minister Mykhailo Koval gave a timetable of days, while Poroshenko said only that the cease-fire would get underway “shortly.”

The peace proposal includes sealing the border with Russia, disarming the insurgents, offering amnesty to those who did not commit serious crimes and providing safe passage to rebels willing to leave the country. The president also promised to pursue constitutional amendments that would decentralize power and grant regional governments more say.

“I can say that the cease-fire time will be pretty short,” Poroshenko told reporters after a speech before graduates of the National Defense University. “We expect that disarmament of military groups and restoration of order will take place right after it.”

But separatists, who have been battling government forces for almost three months, promptly rejected the offer from Poroshenko, whom they said they do not trust.

“This proposal by Poroshenko to lay down our arms is simply a tactical ploy,” said Myroslav Rudenko, a spokesman for the separatists’ self-proclaimed Donetsk People’s Republic, according to the Russian Interfax news agency. “If people fall for it, there will be a new mopping-up operation. We will not put our weapons away.”

And in Moscow, Denis Pushilin, a Donetsk rebel leader, called Poroshenko’s gesture a “pointless proposal.”

“They will stop firing, we will disarm, and they will capture us unarmed — that’s Kiev’s logic,” he said on Russian television. “We don’t think it will be constructive.”

He added: “We are interested in the occupiers leaving our territory, the occupiers who are now systematically destroying us.”

Russian Foreign Minister Sergei Lavrov expressed skepticism at the proposal, saying Russia expects a full-scale, permanent cease-fire. A temporary truce, in which those of pro-Russian sentiment leave the country, he said, “is close to ethnic cleansing.”

This is the third time in less than two weeks in office that Poroshenko has publicly signaled that he will declare a cease-fire. He proposed a truce in his inaugural address June 7, but rebels rebuffed the call. As recently as Monday, he ordered Ukrainian defense forces to seal the porous border with Russia as a prelude to a cease-fire.

In Moscow, Alexei Pushkov, head of the international affairs committee in the lower house of parliament, said the repeated cease-fire proposals were political maneuvering.

“We are told that Kiev is ready to pause, but the pause does not begin,” he said. “It appears that they talk about peaceful plans just as a distraction.”

Poroshenko made no mention Wednesday about what might happen if the rebels refuse to disarm and surrender, although Ukraine’s stand seemed to carry an implicit threat that the war could intensify.

Adding to the sense that more fighting could be on the horizon before there is peace, Ukrainian officials said Russia is continuing a military buildup close to the border between the two countries. Meanwhile, fighting continued in eastern Ukraine, where officials said 15 soldiers had died in the Luhansk region Tuesday night and 13 were unaccounted for.

Residents reached by phone in the port city of Mariupol said a convoy of about 40 Ukrainian army trucks rolled through overnight, heading toward Donetsk. On Twitter, a resident of Kramatorsk, near Donetsk, said trucks carrying weapons to separatists were driven through town.

In Kiev, Poroshenko announced his appointments to a number of key positions. He named Iryna Gerashenko, a member of parliament, as his envoy in peace negotiations. In a move certain to please Moscow, he chose Ukraine’s ambassador to Germany to replace Andrii Deshchytsia as foreign minister. Deshchytsia had displeased many Russians after he used a vulgarity to describe Russian President Vladimir Putin. Deshchytsia’s replacement was described as a routine change that had been expected before the incident.

Alex Ryabchyn in Dniepropetrovsk and Natasha Abbakumova in Moscow contributed to this report.