Kiev (AFP) - Ukrainian President Petro Poroshenko said Thursday he wanted EU and US help in securing Crimea's return from Russia and vowed to win back the separatist east this year.

The bold announcements by the pro-Western leader came with Poroshenko facing building public pressure to end Ukraine's brutal 20-month campaign against pro-Russian insurgents and simultaneously to stand up to Moscow's annexation of the strategic Black Sea peninsula.

Poroshenko provided few details about how exactly he intended to win back Crimea -- a tsarist-era Russian naval base that Moscow annexed just weeks after the ouster of pro-Kremlin Ukrainian president Viktor Yanukovych in February 2014.

He told a wide-ranging press conference that Kiev intended to launch an "international process" aimed at restoring the war-ravaged and economically faltering former Soviet nation's original borders.

"The fight for Crimea's return remains a priority," the 50-year-old political and business veteran said.

"It is my profound conviction that the best format for starting this process is the Geneva-plus format that includes our EU and US partners and possibly the signatories of the Budapest Memorandum."

The 1994 document assured Ukraine of Western and Russian protection from foreign invasion in return for scrapping its Soviet-era nuclear arsenal and accession to the Non-Proliferation of Nuclear Weapons Treaty (NPT).

The pro-Moscow insurgency in the industrial regions of Lugansk and Donetsk began in April 2014 and was immediately linked to alleged efforts by Russian President Vladimir Putin to keep the new Kiev leadership off balance and reliant on Moscow's good will.

Putin denies direct involvement in the conflict but also admitted in December that Russia had "people there who carried out certain tasks including in the military sphere".

"We have irrefutable evidence from both satellite imagery and video footage captured by our intelligence service showing that the Ukrainian border was crossed by Russia's latest military equipment and armed forces units," Poroshenko said.

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Months of laborious European-mediated negotiations have failed to bring a complete halt to a war that has now claimed more that 9,000 lives and left some of Ukraine's most important coal mines and steel mills in ruins.

"In 2016, we must also ensure the renewal of Ukraine's sovereignty over the occupied territories of Lugansk and Donetsk," Poroshenko said.

A new round of talks between top Moscow and Kiev envoys produced a new ceasefire agreement on Wednesday that appeared to be largely holding on Thursday afternoon.

Three Ukrainian soldiers and two pro-Moscow fighters have been reported killed since the start of the year.

- Russian debt -

Ukraine's standoff with Russia has most recently been accompanied by an escalating trade war and a heated disputed over an overdue $3-billion (2.8-billion-euro) loan that Moscow extended to Yanukovych and which cash-strapped Kiev now refuses repay in full.

Poroshenko's team argues that Moscow lent its ally the money on preferential terms as a bribe for Yanukovych's shock November 2013 decision to scuttle a free trade agreement with the European Union that Kiev has since signed.

The new government wants Russia to accept a 20-percent debt write-down -- the same terms accepted last year by Ukraine's private creditors.

Russia has refused and promised to launch legal proceedings against Ukraine in a London court by the end of the month.

Poroshenko repeated that "Ukraine's position (toward Russia) cannot differ from the restructuring conditions that we struck with other investors."

But "we also demonstrate our utmost transparency and willingness to negotiate," the Ukrainian leader added.

"If the Russian side deems it possible, we will immediately begin (new debt) negotiations," Poroshenko said.