Bernie Sanders has denied he was aware of allegations female members of his staff were subjected to sexual harassment during his 2016 presidential campaign.

The Vermont senator apologised on Wednesday “to any woman who felt she was not treated appropriately”, following a New York Times story on Wednesday in which multiple workers made claims about pay inequality and unwanted sexual advances inside the political operation.

There is no suggestion Mr Sanders personally engaged in any impropriety, and he told CNN he had been “a little bit busy running around the country” during the campaign to have known of the allegations at the time.

“I am not going to sit here and tell you that we did everything right in terms of human resources, in terms of addressing the needs that I'm hearing from now, that women felt they were disrespected, that there was sexual harassment which was not dealt with as effectively as possible,” he said.

One female staffer, Giulianna Di Lauro, told The Times a campaign surrogate harassed her repeatedly ahead of the Democratic primary in Nevada in February 2016.

She claimed when she reported the incident to a manager, he told her: “I bet you would have liked it if he were younger,” a version of events corroborated by another witness.

Meanwhile, others told the newspaper the grassroots and decentralised nature of the Sanders campaign left them confused by who to turn to in the event of misconduct.

“I did experience sexual harassment during the campaign, and there was no one who would or could help,” said Samantha Davis, a former director of operations for the campaign in Texas and New York.

The allegations come at an inconvenient time for Mr Sanders, who at 77 is gearing up for a second attempt at securing the Democratic nomination for the presidency in 2020 after missing out two years ago to Hillary Clinton.

He insisted his campaign had introduced new protocols during his 2018 senate re-election bid to deal with allegations made by staffers.

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“We put forward the strongest set of principles in terms of mandatory training, in terms of women, if they felt harassed, having an independent firm that they can go to,” he said.

“I think that that's kind of the gold standard of what we should be doing. Of course, if I run, we will do better next time.”

In the wake of the report, some Democratic activists and operatives complained about the aggressive culture during the first campaign when male staffers and supporters were sometimes labelled “Bernie bros”.

Bernie Sanders campaigns with Hillary Clinton Show all 15 1 /15 Bernie Sanders campaigns with Hillary Clinton Bernie Sanders campaigns with Hillary Clinton Democratic presidential candidate Hillary Clinton, followed by Sen. Bernie Sanders, I-Vt. arrives for a rally in Portsmouth, N.H., Tuesday, July 12, 2016. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton A woman holds a sign at an event where Bernie Sanders will appear with Hillary Clinton at Portsmouth High School July 12, 2016 in Portsmouth, New Hampshire. Sanders and Clinton are expected to show unity within the party and a forwarding of their agendas. Darren McCollester/Getty Bernie Sanders campaigns with Hillary Clinton Cerys Coffey, 5, of North Hampton, Massachusetts, walks along a line of supporters waiting to get into a campaign event with Democratic U.S. presidential candidates Hillary Clinton and Senator Bernie Sanders in Portsmouth, New Hampshire, U.S., July 12, 2016. Mary Schwalm/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton and Sen. Bernie Sanders stand together during a campaign rally where Sanders endorsed Clinton in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton and Sen. Bernie Sanders greet supporters during a campaign rally where Sanders endorsed Clinton in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton speaks as Senator Bernie Sanders looks on after he endorsed her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton (R) looks on as Senator Bernie Sanders endorses her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic U.S. presidential candidate Hillary Clinton looks on as Senator Bernie Sanders endorses her during a campaign rally in Portsmouth, New Hampshire, U.S., July 12, 2016. Brian Snyder/Reuters Bernie Sanders campaigns with Hillary Clinton Democratic presidential candidate Hillary Clinton, followed by Sen. Bernie Sanders, I-Vt., arrives for a rally in Portsmouth, N.H., Tuesday, July 12, 2016, where Sanders endorsed Clinton for president. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Sen. Bernie Sanders, I-Vt. waves as he a Democratic presidential candidate Hillary Clinton arrive for a rally in Portsmouth, N.H., Tuesday, July 12, 2016. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton People hold signs outside an event where Bernie Sanders will appear with Hillary Clinton at Portsmouth High School July 12, 2016 in Portsmouth, New Hampshire. Sanders and Clinton are expected to show unity within the party and a forwarding of their agendas. Darren McCollester/Getty Bernie Sanders campaigns with Hillary Clinton Supporters for Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. cheer before a rally in Portsmouth, N.H., Tuesday, July 12, 2016, prior to the arrival of Clinton and Sanders. Sanders is poised to offer his long-awaited endorsement of Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Supporters of Democratic presidential candidate Hillary Clinton sing the national anthem in Portsmouth, N.H., Tuesday, July 12, 2016, prior to a rally with Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. Sanders is poised to offer his long-awaited endorsement of Democratic rival Hillary Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton Supporters of Democratic presidential candidate Hillary Clinton sing the national anthem in Portsmouth, N.H., Tuesday, July 12, 2016, prior to a rally with Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders, I-Vt. Sanders is poised to offer his long-awaited endorsement of Democratic rival Hillary Clinton, hoping to transfer the energy of his supporters into the party's fight against Republican Donald Trump. Andrew Harnik/AP Bernie Sanders campaigns with Hillary Clinton A woman holds poster for Democratic presidential candidate Hillary Clinton during a rally in Portsmouth, N.H., Tuesday, July 12, 2016, where Sen. Bernie Sanders, I-Vt. endorsed her for president. Andrew Harnik/AP

“I'm not the least bit surprised,” National Organisation for Women president Toni Van Pelt said, adding she was forced to block Mr Sanders’ supporters from her social media feeds in 2016.

“To me, it was really clear this was the way they were running the campaign.”

She cast the blame for the affair on Mr Sanders, whether he had direct knowledge of misconduct or not.

“If he didn't know, he has no business being in office,” she added.