Reuters
Jose Manuel Barroso
"We are in a very serious, I would say, dramatic situation... where we can reach the point of no return," Barroso said, according to Agence France-Presse.
Barroso described the presence of Russian troops in Ukraine as a "new transgression" and predicted further escalation could lead to a tipping point.
"If the escalation of the conflict continues, this point can come," said Barroso.
Despite his warnings, Barroso said he still believed it is not too late for a political solution for the crisis. His remarks came ahead of meetings scheduled for Saturday where EU leaders are expected to launch a new round of sanctions against Russia.
Fighting between Ukrainian troops and pro-Russian separatists has raged for months. Last week, NATO said Russian troops and heavy military equipment crossed Ukraine's border and joined the fighting late this month.
Russia has denied its troops are officially participating in the conflict. Kremlin Foreign Minister Sergey Lavrov responded to satellite images released by NATO that were described as showing Russian forces in Ukraine by claiming, the accusation was "pretty similar" to past instances where he said NATO used "images from computer games" to falsely claim troops were in the country.
Poroshenko also said he hoped there could be a political solution after meeting with EU officials about the crisis. However, he also gave an even more dire warning than Barroso.
"Today we are talking about the fate of Ukraine, tomorrow it could be for all Europe," Poroshenko said.