Leaders from France, Germany, Ukraine and Russia are due to meet in Minsk on Wednesday in a fresh attempt to reach a peace deal in the Ukrainian conflict, but Vladimir Putin said the summit was conditional on some issues being resolved first.

The Russian president, speaking to journalists in Sochi, did not specify what the preconditions were.

“We will be aiming for Wednesday, if by that time we manage to agree on a number of points which we’ve been intensely discussing lately,” he said.

Officials from the four countries are due to meet in Berlin on Monday to make preparations for the Minsk summit. In a concession to Russia, a parallel meeting is due to be held in Minsk that will include separatist representatives.

Alexander Lukashenko, the Belarusian leader, said he expected the summit to take place in the country’s capital on Wednesday evening, adding that he was anxious to see peace return to “our common home” in the region. A previous ceasefire accord was agreed in Minsk in September but it was largely ignored and Moscow-backed separatists in eastern Ukraine have made since significant territorial gains.

The planned summit follows an intense period of top-level diplomacy, which involved a dramatic visit to the Kremlin on Friday by the German chancellor, Angela Merkel, and the French president, François Hollande, in what the latter called “one of the last chances” to avoid a wider war in Ukraine.

The Kremlin meeting was followed by a video conference on Sunday between Merkel, Hollande, Putin and the Ukrainian president, Petro Poroshenko, which Merkel’s office described as “extensive”.

“They continued to work on a package of measures to achieve a comprehensive settlement of the conflict in eastern Ukraine,” it said.

“They (the leaders) expect that their efforts during the Minsk meeting will lead to the swift and unconditional cessation of fire by both sides,” Poroshenko’s office said in a statement. But western diplomats have so far played down expectations from the latest Franco-German peace initiative, saying it was driven by the urgent desire to avoid a new bloodbath in the besieged Ukrainian-held town of Debaltseve, more than any narrowing of differences.

Ukraine and its western supporters are insisting that separatist forces eventually pull back to the ceasefire lines agreed in September, and that a demilitarised zone be established along the frontline. In return, eastern Ukrainian regions would be guaranteed greater autonomy.

Russia wants a ceasefire agreement that recognises the territorial gains won by the separatists since the last Minsk deal.

Merkel is due to meet Barack Obama, the US president, in Washington on Monday, in a bid to synchronise US and western European positions on Ukraine ahead of the Minsk summit.

The mood at a meeting of leaders and foreign ministers at the annual Munich Security Conference was acrimonious. The Russian foreign minister, Sergey Lavrov, was jeered and booed, when he denied Moscow was providing military support to the rebels.

He accused the west of turning a blind eye to extreme nationalists on the Ukraine side who he claimed were bent on ethnic cleansing of non-Ukrainians. His German counterpart, Frank-Walter Steinmeier, criticised Lavrov openly on Sunday.

“It is Moscow’s responsibility to identify common interests,” Steinmeier said. “We have seen too little of this so far. And the speech by my colleague Lavrov yesterday made no contribution to this.”

Monitors from the Organisation for Security and Co-operation in Europe (OSCE) have said that the separatists appear to be benefiting from a constant supply of new weapons and ammunition, and although they assume the arms are coming from Russia, it has been impossible to find out definitively because separatists are denying them access to a 400km section of border that is outside the control of the Kiev government.

The worsening situation, in a conflict that has already cost more than 5,300 lives and driven a million people from their homes, has triggered a debate in Europe and the US over whether to match Russian supplies to the separatists with western deliveries of weapons to the Kiev government. Germany and the UK have declared themselves opposed to arming the Ukrainian army, warning of uncontrolled escalation of the conflict.

Eastern European nations and prominent US senators have backed weapons supplies to Kiev, but the Obama administration says it has yet to make a decision.

The US secretary of state, John Kerry, said at the Munich conference on Sunday, that the differences between the western allies were “tactical not strategic”.

Speaking at the same forum on Saturday, the vice-president, Joe Biden, said the US would continue to provide “security assistance” to the Ukrainians, an apparent reference to supplies of US non-lethal equipment such as vehicles and medical supplies, although half of the promised deliveries have failed to materialise.

Poroshenko said Ukraine would welcome supplies of more non-lethal equipment such as counter-barrage radar (that can identify the source of artillery fire), communications and radio jamming technology. Diplomats in Munich said it was possible the debate over arming Kiev could be resolved by an expansion of the current policy of non-lethal support to include items such as those listed by Poroshenko.