The presidents of the European Commission and Ukraine cautioned Russia against escalating the conflict in eastern Ukraine Saturday. (Reuters)

A senior European official warned Saturday that the crisis in eastern Ukraine might soon “reach the point of no return” as European nations looked at stiffening sanctions against Russia, possibly within a week.

José Manuel Barroso, president of the European Commission, stressed that it was “not yet too late to find a political solution” to the fighting between Ukrainian troops and pro-
Russian separatists, even as new evidence emerges of Russian support for the rebels.

But he added that European leaders “have already prepared some options” on sanctions, and surmised they will “be ready for a new round of sanctions following the recent escalation” and any further destabilization of Ukraine.

Barroso made his comments Saturday after meeting with Ukrainian President Petro Poroshenko. He added that he had communicated his concerns to Russian President Vladi­mir Putin in a phone call Friday.

“The opening of new fronts and the use of Russian regular forces is not acceptable and represents a grave transgression,” Barroso said Saturday. “Russia should not underestimate the European Union’s will and resolve to stand by its principles and values.”

Barroso’s comments were some of the strongest diplomatic condemnation of Russia to emerge from the European Union since member nations imposed economic sanctions against Russia in July, targeting the country’s defense, energy and financial services industries. The new sanctions, should they be imposed, would probably affect broad sectors of the economy as well, though European leaders did not detail what steps were considered Saturday. The European Commission is the executive arm of the E.U.

Another official, Herman van Rompuy, president of the European Council, said that it was asking the commission to “present proposals for consideration within a week” on new sanctions. The council gives political direction to the European Commission.

Poroshenko went to Brussels Saturday to urge a meeting of European heads of state and government to both stiffen sanctions against Russia and help Ukrainian forces with military assistance, in light of what Ukrainian officials call Russia’s recent incursions into their country. The pro-Russian rebels have regained some territory in the last few days, after weeks of losing ground to Ukrainain troops.

“Ukraine is now an object of foreign military aggression,” Poroshenko said in Brussels, arguing that the situation in his nation was considerably worse than even just a few days ago. “It is a very high risk not only for peace and stability in Ukraine, but also for the entire Europe.”

Russian officials have repeatedly rejected accusations that their government is sending weapons, military vehicles and troops over the border to assist separatists in Ukraine. They have said some Russians who support the separatists’ cause have crossed the border as volunteers.

NATO has cited evidence presented by Ukrainian authorities as well as its own satellite imagery to determine that Russia has been supplying separatists with military material and firing on Ukrainian forces — including from within Ukraine itself.

On Friday, Putin gave his most direct statement yet in support of the separatists, hailing them as “insurgents” battling an army that he likened to Nazi invaders during World War II, and praising them for “suppressing the power operation of Kiev” in Donbas, a reference to the Donets basin of eastern Ukraine, the area separatists are trying to claim as their territory.

Russian military allegedly enters Ukraine and attacks its forces.

He spoke a day after the government in Kiev said Russian soldiers, tanks and heavy artillery had begun rolling into the region to help the separatists reverse Ukrainian military gains.

Meanwhile, Poroshenko confirmed to European leaders Saturday that Ukraine intends to ratify its association agreement with the E.U. in September. Ukraine’s parliament will also probably consider a new draft bill to repeal the country’s “non-bloc status,” which prevents it from aligning with a military alliance such as NATO. Ukrainian Prime Minister Arseniy Yatsenyuk said that could pave the way for Ukraine seeking NATO membership.