"We have more than 9,000 troops of the Russian Federation on my territory, including more than 500 tanks and heavy artillery and armed personnel carriers," Poroshenko told the World Economic Forum in Davos.
The pro-Western leader stressed there was no military solution to the brutal nine-month conflict that has killed more than 4,800 people and brought Ukraine's economy to its knees.
But he insisted that the key to peace was held by Russia — a country that has firmly denied supporting the insurgents despite NATO satellite imagery purporting to show its forces' presence in Ukraine.
"The solution is very simple. Stop supplying weapons. Stop supplying ammunition. Withdraw the troops and close the border. A very simple peace plan," Poroshenko said to a round of applause.
Poroshenko — elected in May on a promise to bring his ex-Soviet republic under the military protection of NATO and within the 28-nation EU — repeated his urgent call on Western powers to supply Ukraine with modern weapons that could ward off a Russian attack.
"We have a very strong army to defend our territory," he said in English.
"But defensive technology is also the things which we need, because only a strong army can help us keep the territory," he said.
"Political, economic, defensive and moral support — these are the four key ingredients for supporting Ukraine," said the 49-year-old leader.
Poroshenko's previous appeals to US President Barack Obama to supply Ukraine with offensive weapons have been rebuffed by a White House concerned that such deliveries would lead to only more problems with Russia.
The United States and some NATO member states have been supplying Ukraine's cash-strapped forces with military equipment such as night vision goggles and armour.
But Poroshenko insists that more equipment is needed to help soldiers quell the eastern revolt.
Ukraine's economic problems caused by extra war spending and the eastern region's industrial collapse were last year compounded by a months-long cut of Russian gas supplies.
The dispute stemmed from a disagreement over prices.
Kiev accused Moscow of using gas as a means of "economic agression" and refused to pay the higher rates Russia slapped on Ukraine in the wake of last February's ouster of a Kremlin-backed president.
Poroshenko said Ukraine in the past year halved the amount of gas it imported from Russia and insisted that this trend would continue in the months to come.
He vowed to completely break Ukraine's expensive energy dependence on Russia by 2017 with the help of a transition to western European imports and his country's own shale gas supplies.
"I am absolutely sure that in two years' time, we will be absolutely energy independent from Russia," said Poroshenko.
"We have an absolutely new way for receiving our European gas," he said.
"We will have shale gas technology inside the country."
Meantime, International Monetary Fund head Christine Lagarde said on Wednesday that Poroshenko has asked the Washington-based IMF for a new and broader rescue package.
Lagarde met Poroshenko on the sidelines of the Davos gathering.
"President Poroshenko informed me today that the Ukrainian authorities have requested a multi-year arrangement with the Fund . . . to replace the existing . . . arrangement," Lagarde said in a statement.
"We will consult with the IMF Executive Board on the authorities' request," she said.
The IMF, which last year granted Kiev $17 billion (13.6 billion euros) in financial aid over two years as part of a broader $27 billion global rescue package, has expressed fears that the former Soviet country may need an additional $15 billion in immediate aid.
The Ukrainian government said the request was key to turning around the war-torn economy.