The finance ministers of the Group of Seven economic powers want to put together a 15 billion euro ($15.8 billion) aid package for Ukraine at their meeting in Bonn this week, a senior German government official said on Tuesday.
The package would cover three months, with a short-term financing arrangement mainly in the form of grants, which unlike loans do not have to be repaid, the official said, adding that the aid was needed because Ukraine's revenues have collapsed.
The United States had already offered to contribute half of the aid in the form of grants worth $7.5 billion, the official said, adding that the G7 ministers wanted to agree a joint communique at their meeting starting on Wednesday.
Earlier, German Finance Minister Christian Lindner was quoted as saying there was also a discussion among Western powers about how Russia could be made to help pay for the massive, longer-term task of rebuilding Ukraine.
"I am politically open to the idea of seizing foreign assets of the Russian Central Bank," Lindner said in an interview with German business daily Handelsblatt and three other European newspapers.
"In the case of private assets, we have to see what is legally possible," Lindner added. "We have to respect the rule of law, even if we are dealing with Russian oligarchs."
Some EU politicians have called for the use of Russian assets frozen by the West, including some $300 billion of Russian central bank reserves, as reconstruction money for Ukraine once the war ends.
But there are reservations about the legality of such a move on both sides of the Atlantic. Kremlin spokesman Dmitry Peskov said on Tuesday it would be "outright theft".
A US Treasury official speaking on condition of anonymity said there were legal, policy precedent-setting and political issues to consider, adding that there was a risk that confiscating frozen assets could impede negotiations to end the war.
The official said Washington was currently more focused on meeting Ukraine's immediate budget needs over the next three months than on massive reconstruction and asset disposition.
($1 = 0.9496 euro)