Donald Trump's aides spoke with Russian officials during presidential campaign

Feb. 15 (UPI) -- U.S. intelligence and law enforcement officials say advisers to President Donald Trump were in contact with known Russian intelligence agents during his presidential campaign.

Four U.S. government officials told The New York Times several high-ranking aides to Trump were in regular contact with senior Russian intelligence officials before the presidential election in November, based on conversations intercepted and analyzed by U.S. intelligence agencies.

Several law enforcement, intelligence and administration officials told CNN that frequent communication during summer 2016 got the attention of agencies while they were collecting routine intelligence on Russian officials and nationals.

The officials say the communications were discovered as part of normal information gathering on Russia and they are still trying to determine the motive for the communications.

Former national security advisor Michael Flynn, who was one of Trump's top advisors during the campaign and who resigned Monday night for misinforming Vice President Mike Pence about a conversation with a Russian diplomat, is among the aides identified as having communication with Russian agents.

The Federal Bureau of Investigation and National Security Agency have been reviewing intercepted calls between Paul Manafort, one of Trump's former campaign managers, and Russian agents, though he denies any knowledge they were intelligence agents.

"I have never knowingly spoken to Russian intelligence officers, and I have never been involved with anything to do with the Russian government or the Putin administration or any other issues under investigation today," Manafort said Tuesday. "It's not like these people wear badges that say, 'I'm a Russian intelligence officer.'"

Manafort, like Trump and several of his family members, aides and associates, has done business in Russia, which often brings one in contact with members of their spy services. The U.S. officials did not disclose the details of any of the calls they are investigating or who was on them.

Among other aides to the campaign and administration the FBI has investigated for contact with Russia, possibly after intercepting other conversations, are former foreign policy advisor Carter Page and Republican strategist Roger Stone.