A ceasefire signed by Kiev and pro-Russian rebels after marathon talks between the leaders of Ukraine, Russia, Germany and France comes into force Sunday, the first step in a peace deal aimed at ending 10 months of conflict.

The fragile agreement reached in Minsk Thursday is seen as the best hope to end fighting but scepticism runs high after the collapse of a similar deal and the plan is fraught with potential sticking points.

Here are some of the most likely obstacles to peace:

Ceasefire

Both sides have agreed to stop fighting from 00:00 Sunday Ukraine time (2200 GMT Saturday) but surging violence in the run-up to the deadline has cast doubt on whether this will hold. Previous ceasefire deals have failed to stop the clashes.

Ukrainian troops were clinging on to the railway hub of Debaltseve but were nearly encircled by rebel forces. Other potential hotspots are around the airport in the rebel stronghold of Donetsk and the key Kiev-held port city of Mariupol.

Withdrawal of heavy weapons

Following the start of the ceasefire both sides have two days to begin pulling back heavy weapons from the frontline. The ambitious aim is to create a buffer zone of between 50-140 kilometres (31-87 miles) within two weeks depending on the range of the weapons.

Enforcement

The mammoth task of monitoring the ceasefire and withdrawal of heavy weapons falls to some 350 civilian Observers from the Organization for Security and Co-operation in Europe. The monitors however lack any concrete powers to enforce the truce and have failed to ensure earlier ceasefires.

Status of rebel regions

Thrashing out the long-term status of the rebel regions is set to be a major source of contention. Under the Minsk agreement, discussions should start on holding local elections under Ukrainian law the day after heavy weapons are withdrawn.

By mid-march Ukraine must adopt a law demarcating the territories to be granted special status and is obliged to adopt a new constiution by the end of 2015 that includes the "decentralisation" of powers to the regions.

Meanwhile, Ukraine will have to ressume social welfare payments to those living in the separatist areas and reestablish the banking system.

Amnesty

Under the deal, Ukraine is obliged to implement an amnesty for those involved in the uprising. However, this has raised fears abroad that those behind the downing of Malaysia Airlines flight MH17 will be let off. Ukraine has insisted that those guilty of crimes against humanity will not be eligible for amnesty.

Border control

Ukraine sees re-establishing its control over some 400 kilometres (250 miles) of its border with Russia as crucial to stopping arms and fighters flooding its territory. The agreement however only foresees Kiev taking charge by the end of 2015 after local elections are held.

Prisoners

Ukraine and the rebels are expected to exchange all the prisoners they hold five days after heavy weapons are pulled back. One stumbling block is the fate of Ukrainian pilot Nadia Savchenko who is currently on hunger strike in detention in Moscow, after Kiev says she was illegally spirited into Russia.

Withdrawal of foreign forces

The Minsk agreement only has one line about the withdrawal of foreign troops from Ukraine. Kiev says Russia has sent thousands of soldiers onto its territory but Moscow denies this.