US Attorney General Jeff Sessions did not disclose meetings he held with Russian officials in his application for security clearance, the Justice Department has said. The revelation on Wednesday (24 May) comes on the heels of a report that Russian officials had discussed how to influence Donald Trump's aides last summer.

Officials said that Sessions failed to report meetings he had with Russian ambassador Sergey Kislyak last year on the form. The application for security clearance requires applicants to list "any contact" they or their family had with a "foreign government" or its "representatives," CNN reported.

Justice Department spokeswoman Sarah Isgur Flores told CNN that Sessions initially listed a year's worth of meetings with foreign officials.

However, an FBI employee assisting Sessions in filling out the form, known as the SF-86, told him and his staff that he did not have to list the dozens of meetings with foreign ambassadors while he was senator.

CNN reported that federal officials are not required to list meetings they had as part of a foreign conference he or she attended while conducting government business to obtain security clearance.

Sessions has been criticised by Democrats after it was revealed that he did not disclose his two meetings with Kislyak during his Senate confirmation hearings earlier this year. Questions have arisen about his meetings with Russian officials while part of the Trump campaign, as well as his role in sacking FBI Director James Comey.

According to CNN, Sessions could be called to testify before the House and Senate intelligence committees as part of their ongoing investigation into possible collusion between the Trump campaign and Russia. The Department of Justice also announced earlier in May that a special counsel had been appointed to probe Russian interference.

News of Sessions' omission on his security clearance form was released shortly after the New York Times reported discussions by Russian intelligence and political officials last summer on how to use Trump's aides to exert influence over him.

American spies collected conversations focused on Paul Manafort, a former Trump campaign chairman, and Michael Flynn, an adviser to the Trump campaign.

Russian officials reportedly were confident that both men, who had indirect ties to Moscow, could be used to shape Trump's opinions on Russia. In some conversations, Russians bragged about how well they knew Flynn, while others spoke about leveraging their ties to ousted Ukrainian president Viktor Yanukovych, who had previously worked with Manafort.

US intelligence picked up the conversations while investigating Russian attempts to interfere in the presidential election. Information about direct communications between Trump's advisers and Russian officials was also collected.

The Times noted that it remains unclear whether Russian officials actually attempted to influence Manafort or Flynn. Both have denied collusion with Russia.