Kiev (AFP) - Ukraine is rearming and deploying newly formed units to protect cities in the east of the country from threatened attempts by pro-Russian rebels to seize more territory, President Petro Poroshenko said Tuesday.
At a crisis meeting of security chiefs in the capital Kiev, Poroshenko said he had not given up on a deal brokered in September to end the seven-month conflict, in which the UN says more than 4,000 people have died.
"Ukraine remains a firm supporter of the peace plan," Poroshenko said.
However, Poroshenko said Ukraine's military is ready to repel any separatist attempt to mount a new offensive, as they have repeatedly threatened to do.
Troops were in place to defend government-held cities from Mariupol on the Black Sea to Kharkiv in the northeast, near Russia, he said.
"We are obliged as the Ukrainian state not to allow the spread of this cancerous tumour, to ensure the blockade of this territory," he told his National Security and Defence Council.
Ukraine's small army has been badly mauled during the more than half-year of battles with rebels who Western governments say are supplied and supported by regular Russian troops.
NATO chief Jens Stoltenberg said on Tuesday in Brussels that Russia continues to arm, train and support the rebels, with special forces inside Ukraine and more troops detected moving troops along the border.
But Ukraine will be "prepared for decisive measures in the case of a negative scenario," Poroshenko said.
"Today, several new units and groupings have been formed, which will already allow us to stop any possible attack," he said. "The supplying of our armed forces with the very latest technology -- offensive, reconnaissance, guided systems -- is continuing quite effectively."
- Autonomy offer scrapped -
The meeting with security chiefs in Kiev was called after separatists staged leadership elections that were endorsed by Russia, but condemned by Ukraine, the United States, EU powers, and the head of the United Nations.
In the two rebel enclaves in the east, centred on the cities of Donetsk and Lugansk, the Kremlin-backed leaders added to the trappings of statehood with post-election inauguration ceremonies Tuesday.
Poroshenko said the "pseudo" elections on Sunday had "torpedoed" a key provision of the September peace deal in which rebels would be given wide autonomy, while preserving Ukraine's integrity.
The September accord -- signed by Ukraine, the rebels, Russia and the European security body OSCE in Minsk -- was meant to pave the way for a ceasefire and ultimately a political settlement.
Poroshenko said he had now decided to ask parliament to "cancel" the law offering autonomy for the rebel regions, a measure at the heart of the whole peace plan.
Constant ceasefire violations have already undermined the truce, with fighting breaking out again across the conflict zone on Tuesday. Ukraine's military announced the death of one soldier and five wounded.
Artillery bombardments started up outside Donetsk, AFP correspondents said. Observers from the OSCE said there had also been artillery fire in several other areas of southeastern Ukraine.
A drone used to help the observers came under "military grade" jamming, the OSCE said, adding that Ukrainian forces immediately said they were not responsible. On Sunday another OSCE drone came under anti-aircraft fire.
- Gas wars -
Ukraine's state-owned gas group Naftogaz announced it had paid the first part of its debt to Russia's Gazprom, in order to get deliveries flowing again ahead of winter.
The payment of $1.45 billion is just under half of the total $3.1 billion owed, which according to a deal done in October must be fully repaid by the end of the year for Russia to keep the taps on in 2015.
The deal was reached last month in EU-brokered negotiations that ended a long dispute between major gas supplier Russia and the ex-Soviet republic.
Poroshenko, meanwhile, warned that his cash-strapped central government would consider cutting gas and electricity supplies to the rebel region in the east.
"Under the law we should have long ago cut heating and energy," he said.
Such a move would put severe pressure on rebel leaders, who would likely seek aid from Russia, but also add to the growing evidence of Ukraine being cut permanently from its separatist territories.
- Angry international reaction -
The United States blasted the rebel elections and Moscow's endorsement of the polls, warning the Kremlin against any new rebel offensive.
"Any attempt to push further into Ukraine would be another violation of Ukraine's sovereignty and territorial integrity and a gross violation of the Minsk agreement signed by Russia, Ukraine and the separatists," State Department spokeswoman Jen Psaki said.
Although Moscow has not recognised the rebel statelets' independence, its statement that it "respected" the elections' validity was also likely to stiffen US and EU resolve on maintaining punishing sanctions against Russia.
The new EU foreign policy chief, Federica Mogherini, said the rebel elections threatened to scuttle any chance of a peaceful solution.
"The main risk I see now is that we close this window of opportunity for internal dialogue and for dialogue with Russia" on implementing a peace plan all sides agreed in September, Mogherini said at a press conference.