Newly released documents from Special Counsel Robert Mueller's investigation have revealed that Steve Bannon, Donald Trump's erstwhile campaign manager and chief strategist, apparently worked to damage presidential adviser Jared Kushner.

The previously-unseen documents, 274 pages of Mueller team interview notes, and emails were released by the Justice Department on Saturday. It was part of a Freedom of Information Act lawsuit filed by two popular media companies. The documents claim of a vacation Jared Kushner and Ivanka Trump took in Croatia with a mystery 'Russian billionaire' during the 2016 Presidential campaign.

According to the notes, Steve Bannon raised questions about the vacation and found them dubious enough to use it against Donald's Trump's son-in-law. The former White House Chief Strategist hoped to "leverage" Kushner's alleged vacation with the Russian businessman, in which Rupert Murdoch's former wife Wendi Deng was also present, reports Daily Mail.

"Bannon knew Kushner was on vacation off the coast of Croatia with a Russian Billionaire when Bannon took over the campaign," a summary of Mueller's investigative interview with Bannon read. The summary does not name the Russian billionaire and his girlfriend.

"Bannon said his friends in the intelligence community said the girlfriend was 'questionable'. Bannon called Kushner and told him to come back from vacation. They had 85 days to go, no money and they needed Kushner to come back and fire Paul Manafort," the summary of investigators' interview with Bannon further states.

Pictures of Kushner and the first daughter aboard the mega yacht of billionaire Democrat donor David Geffen, and jet skiing off a $200 million boat were also published earlier. Wendi Deng was also photographed with the couple, however, the said Russian billionaire was not seen.

Ivanka Trump and Jared Kushner
President Donald Trump's daughter Ivanka Trump and her husband Jared Kushner have angered their new neighbours Getty

The released documents feature an email dated July 24, 2017, sent by Bannon to an individual with a Breitbart domain email. Bannon talks about Kushner's Croatia vacation in the email and suggests the information if reported and confirmed could be valuable against the latter.

Bannon is the co-founder and former executive chairman of the conservative website Breitbart News. The name of the Breitbart employee has been revealed in the released documents.

Bannon's seven-month stint in the White House was marked by widely-publicised clashes with other administration officials and a bitter power struggle with Kushner and Ivanka.