Ukraine crisis: Rebel 'status' row threatens truce deal
Ukraine's MPs have approved changes to the "special status" law for parts of rebel-held areas in eastern Ukraine.
The law will now come into force only after local elections monitored by international observers are held in the areas according to Ukrainian law.
The amendments also envisage the pullout of "all illegal armed groups" from the Donetsk and Luhansk regions.
Pro-Russian rebels and Moscow accuse Ukraine of introducing new terms that threaten last month's ceasefire deal.
Following the agreement in Minsk, Belarus, the ceasefire took effect on 15 February and has largely held despite sporadic shelling.
Both Ukraine and the rebels claim to have withdrawn heavy weapons from the line of contact.
'Temporarily occupied territories'
The changes to the "special order of self-government" in parts of the two eastern regions were adopted after heated discussion in parliament in Kiev on Tuesday.
The law itself was approved last year.
Self-government for the pro-Russian rebel areas is a key part of the Minsk deal, and Mr Poroshenko's new legislative proposals are aimed at furthering that agreement.
But a Russian Foreign Ministry statement (in Russian) said the proposals put before Ukrainian MPs included "additional terms never previously discussed".
The ministry said President Poroshenko had "totally ignored" Minsk provisions calling for dialogue with the pro-Russian rebels on arrangements for local elections and the regions' future status.
A statement from a Donetsk rebel leader, Denis Pushilin, also castigated Mr Poroshenko over the "non-agreed amendments", which he said "breach the spirit and letter of the Minsk accords".
Mr Pushilin said "the Minsk process is in fact interrupted" because Mr Poroshenko "does not respect the Donbas [Donetsk and Luhansk] people, he does not want peace".
Mr Poroshenko's bill says special status would have to follow local elections held in accordance with Ukrainian law and under international observation.
In addition, he says the elections would have to take place without any presence of "mercenaries" and with open access for Ukrainian media.
Separately, Ukrainian MPs adopted a resolution describing as "temporarily occupied territories" parts of the Donetsk and Luhansk regions.
The Kiev government, Western leaders and Nato say there is clear evidence that Russia has helped the rebels with troops and heavy weapons. Russia denies that, insisting that any Russians on the rebel side are "volunteers".
More than 6,000 people have been killed in clashes since the rebels seized large parts of the Donetsk and Luhansk regions last April - a month after Russia annexed Ukraine's southern Crimea peninsula.