European Union leaders meeting on July 16 could approve new sanctions against Russia and pro-Russian separatists in Ukraine.
Diplomatic sources say the 28-member bloc's leaders are likely to give a green light to expanding the list of Ukrainians and Russians targeted with EU asset freezes and visa bans.
Diplomats say EU leaders could agree to broaden the scope of those targeted with sanctions, and to take some unspecified additional measures.
However, measures are reported to fall short of the tougher sanctions against the Russian economy that the United States and some EU members, including Poland and the Baltic states, have lobbied for.
Some major member states, such as Italy and Germany, have strong economic ties with Moscow.
Meanwhile, U.S. and EU officials said on July 15 that Washington is considering imposing unilateral sanctions on Russiaout of frustration with the EU's lack of tougher action against Moscow.
However, the White House said in a statement on July 15 that U.S. Vice President Joe Biden told Ukrainian President Petro Poroshenko that Washington "was engaging with European leaders to discuss the imposition of costs on Russia for its continued escalation of the conflict."
So far, the EU has imposed asset freezes on 72 people and two energy companies in Ukraine's Crimea region, which was annexed by Moscow earlier this year.
The White House also said Poroshenko told Biden that Ukraine tried to arrange an OSCE-facilitated meeting including the separatists, Russia and Ukraine, but the separatists refused to attend.
In a separate statement, the White House said that President Barack Obama and German Chancellor Angela Merkel, in a phone call on July 15, also agreed "to ensure that Europe and the United States remain closely coordinated" on sanctions.
On July 15, at least 11 people were reportedly killed in eastern Ukraine when an apartment building was destroyed by explosions.
Kyiv officials have denied pro-Russian separatists' claims that a Ukrainian air strike caused the destruction on July 15 in the border town of Snizhne, in the Donetsk region.
Ukrainian Security Council spokesman Andrei Lysenko called the incident a "cynical and bloody provocation."
He said Ukrainian aircraft had not flown any sorties at the time of the explosions and suggested Russia had a role in the incident.
Ukraine's military said on July 15 that 258 of its soldiers were killed, more than 900 injured, and 45 had been captured during its three-month-long military campaign in the east.
In the last two weeks, Ukrainian forces have cut in half the territory in eastern Ukraine that is held by the separatists, many of whom have fled to the regions' capitals of Luhansk and Donetsk.
Based on reporting by Reuters, AFP
