Donald Trump’s ex-campaign chairman and a former business associate have surrendered to federal authorities over the first charges stemming from the investigation into possible Russian links to Mr Trump’s presidential campaign.

Paul Manafort and Rick Gates surrendered to federal authorities in Washington, and are expected in court later on Monday to face charges brought by Robert Mueller’s investigation team, according to sources.

Rick GatesRick Gates (AP Photo/Evan Vucci, File)

Mr Mueller was appointed as special counsel in May to lead the Justice Department’s investigation into whether the Kremlin worked with associates of the Trump campaign to influence the presidential election last year.

The appointment came a week after the firing of James Comey, who as FBI director led the investigation, and also followed the recusal months earlier of attorney general Jeff Sessions from the probe.

Investigators have focused on associates including Manafort, whose home was raided in July by agents searching for tax and international banking records, and ex-national security adviser Michael Flynn, who was forced to resign in February after White House officials said he had misled them about his conversations with the Russian ambassador to the US.

Manafort joined Mr Trump’s campaign in March last year and oversaw the convention delegate strategy. Mr Trump pushed him out in August amid a steady stream of negative headlines about his foreign consulting work.

Donald TrumpPaul Manafort was Donald Trump’s former campaign chairman (Evan Vucci/AP)

Mr Trump’s middle son, Eric Trump, said in an interview at the time that his father was concerned that questions about Manafort’s past were taking attention away from the billionaire’s presidential bid.

Manafort has been a subject of a long-standing FBI investigation into his dealings in Ukraine and work for the country’s former president, Viktor Yanukovych. That investigation was incorporated into Mr Mueller’s broader probe.

The investigation has also reached into the White House, as Mr Mueller examines the circumstances of Mr Comey’s firing. Investigators have requested extensive documents from the White House about key actions since Mr Trump took office and have interviewed multiple current and former officials.

Mr Mueller’s grand jury has also heard evidence about a June 2016 meeting at Trump Tower attended by a Russian lawyer as well as Manafort, Donald Trump Jr, and the president’s son-in-law, Jared Kushner.

Gates was Manafort’s chief deputy and a key player from Mr Trump’s campaign who survived Manafort’s removal last summer. Two weeks ago, he was still working for Tom Barrack, a Trump confidant, helping with the inauguration committee’s campaign account.