Former White House chief strategist Steve Bannon and ex-Trump campaign manager Corey Lewandowski have been asked to testify before House investigators probing Russian interference in the 2016 election.

The House Intelligence Committee this week sent letters to the two men requesting that they both appear voluntarily before the panel in January, according to Bloomberg Politics.

The invitations have yet to be accepted and, if the interviews proceed, they will likely be conducted behind closed doors, an official familiar with the committee's schedule told the news outlet.

Neither Bannon nor Lewandowski have been publicly accused of any wrongdoing, but the letters suggest the committee's line of questioning will pertain to possible links between Trump and the Kremlin.

Bannon held a prominent position at the Trump White House when former national security adviser Michael Flynn and ex-FBI Director James Comey were fired.

He was also an intermediary between the campaign and Cambridge Analytica.

The data analytics firm's CEO, Alexander Nix, has already been questioned by the panel over potential links between the organization, WikiLeaks, and Democratic National Committee email hacks.

Lewandowski allegedly received communications from former Trump foreign policy adviser George Papadopoulos regarding his contacts with the Russian government.