Russia is asking China for both military and economic assistance, according to reports in the Financial Times and New York Times newspapers.
Moscow wants Beijing to provide military supplies to use in Ukraine, the FT says.
Citing unnamed US officials, the FT reported that Russia had been requesting Chinese equipment since the start of the invasion. The officials declined to specify what kind of equipment Russia is seeking.
The report added that there were indications that China may be preparing to help.
A separate report in the New York Times - again citing US officials - alleges Russia is also asking for economic assistance to mitigate the impact of sanctions.
China has so far sought to portray itself as neutral in the Russia-Ukraine conflict and has not condemned the invasion.
On Monday US National Security Adviser Jake Sullivan is expected to hold talks with a top Chinese foreign policy official, Yang Jiechi, in Rome.
Speaking to NBC on Sunday, Sullivan said the US would "ensure that China nor anyone else" can compensate Russia for its economic losses.