(CNN) A grand jury has subpoenaed former Republican Rep. Pete Sessions on matters connected to President Donald Trump's personal attorney Rudy Giuliani, two Giuliani associates' dealings with Ukraine and efforts to remove the US ambassador to Ukraine, sources familiar with the matter told CNN.

Sessions' subpoena suggests that investigators are looking to gather information on his interactions with Giuliani, as well as with associates Lev Parnas and Igor Fruman -- who were indicted for allegedly funneling foreign money into US elections -- as the investigation into their Ukraine dealings charges forward.

The subpoena to Sessions came in the last few days after the indictment against Parnas and Fruman was made public, according to the source and another source familiar with the matter.

The second source refused to rule out that Sessions himself is not a target of the grand jury investigation, saying instead that the investigation has "not reached definitive conclusions."

The Wall Street Journal first reported that Sessions had been subpoenaed.

Sessions "is cooperating with the US attorney from the Southern District of New York and will be providing documents to their office related to this matter over the next couple of weeks as requested," spokesman Matt Mackowiak said.

Mackowiak declined to specifically comment on reports that Sessions had received a grand jury subpoena for documents related to Giuliani's Ukraine dealings and his communications with Giuliani, Parnas and Fruman.

A spokeswoman for the Manhattan US attorney's office declined to comment on the subpoena.

Giuliani said Saturday that he's not aware he's under investigation for his involvement in the unraveling Ukraine scandal.