By Mark Hosenball

WASHINGTON (Reuters) - U.S. lawmakers are pressuring the Justice Department for access to counterintelligence reports generated by Special Counsel Robert Mueller during his investigation of President Donald Trump and his associates, two congressional sources said on Tuesday.

Mueller's team produced counterintelligence reports and passed the information along to the FBI and the Justice Department based on witness interviews and other evidence about Russia's attempts to interfere in the 2016 U.S. presidential election.

Intelligence committees in both the Democrat-led House of Representatives and the Republican-led Senate want detailed information about those reports and leads, the congressional sources said.

In a footnote to one section of his report about a Russian operation that trolled American internet users during the 2016 campaign, Mueller said his team was "aware of reports that other Russian entities engaged in similar active measures operations targeting the United States."

U.S. and European law enforcement and intelligence officials have said European spy agencies began collecting information about Russian government hackers' efforts to target U.S. government and political networks as early as 2015.

FBI investigators also started probing hacking of the Democratic Party in late 2015, sources familiar with the investigations said.

Last week, in a letter to Attorney General William Barr, House Intelligence Committee chairman Adam Schiff said the Justice Department failed to comply with a subpoena his committee issued for documents and materials related to Mueller's investigation.

Schiff said that failure to comply "places the Department at risk of unlawfully withholding foreign intelligence and counterintelligence information from the committee."

He also said the committee could consider enforcement action against the department at a meeting scheduled for Wednesday if the requested materials are not produced.

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Last month, according to a congressional source, the bipartisan leadership of the Senate Intelligence Committee wrote the FBI requesting a briefing on counterintelligence information developed by Mueller's team. The source said that briefing had not yet occurred.

The Justice Department has offered to let the House committee's members see most of the redacted parts of Mueller's report on Russia's role in the 2016 U.S. presidential election as well as foreign and counterintelligence documentation related to Mueller's inquiry.

In a letter sent to Schiff on Tuesday, Justice Department official Stephen Boyd said he was surprised that Schiff's committee had found that proposal "unacceptable".

Boyd also said the department was willing to discuss a possible plan for giving Intelligence Committee members and staff closed-doors access to some additional material they are seeking if Schiff does not move forward with his threats to hold the department in contempt.

(Reporting by Mark Hosenball; Editing by Lisa Shumaker)