British Cycling chief executive Ian Drake was is facing awkward questions over the crisis which has engulfed one of Britain's most successful Olympic and Paralympic sports.

Shane Sutton resigned as technical director yesterday, while refuting claims of discrimination which will be investigated in an independent review.

But Drake was under growing pressure to reveal what he knew about the "culture of fear" which is alleged to have prevailed in the National Cycling Centre, known as the 'Medal Factory'.

Two separate sources have indicated that Drake was aware of claims of bullying and discrimination against Sutton and did not act.

British Cycling said the report would be made available in the review process.

A statement from the governing body read: "British Cycling conducted a comprehensive structural review after London 2012 to look at how we could build on that success.

"The report will now be made available to the independent review led by UK Sport.

"Until the review is concluded, we cannot comment any further."

Britain won eight gold medals at the 2008 Olympics and 2012 Games - claiming seven out of 10 events on the track at each Games - when Dave Brailsford was performance director and Sutton his right-hand man as head coach. Britain won 25 more golds in the 2008 and 2012 Paralympics.

An internal performance review conducted after the London 2012 Games saw more than 40 riders and staff interviewed.

But the report, written by Peter King, Drake's predecessor as the organisation's chief executive until 2008, was never published or made available to senior personnel. It remains confidential.

Sutton was named technical director of British Cycling, succeeding Brailsford, in April 2014.

But it has emerged Sutton did not declare that he was still an employee of Team Sky, the British road team run by Brailsford and with close links to British Cycling, when he took on the role.

Drake, in a BBC interview on Wednesday evening, answered "no" when asked if Sutton was still employed by Team Sky.

Sutton, who was unavailable for commen, left his role as Team Sky head coach in January 2013, but is still employed in an advisory role.

The role could be perceived as nepotism as Brailsford and Sutton have enjoyed a long and successful working relationship and are good friends.

However, British Cycling had no concerns over Sutton's work for them and Team Sky employs numerous British riders who also compete for Great Britain.

Team Sky on Thursday said Sutton's position has not been a secret - but they would not disclose his remuneration and further details of his employment.

"Shane has continued to be used by Team Sky in an occasional advisory role," a statement from Team Sky read.

"Since he stepped down as head coach of Team Sky in January 2013 his occasional involvement as an advisor to Team Sky has been completely separate from his role with British Cycling.

"Any reimbursement for his work with Team Sky has been funded by the team."

The relationship between Team Sky and British Cycling was subject of a review by auditors Deloitte, with the findings published in March 2011.

Among the conclusions was the need for those working in dual roles - for both Team Sky and British Cycling - to be monitored "from a resource and financial perspective".

That report identified "no major risks" and a positive influence of Team Sky on British Cycling.

Sutton was suspended by British Cycling on Tuesday after it was claimed he called Paralympic cyclists "gimps", shortly after announcing an independent review into claims of sexism made by Jess Varnish. He quit less than 24 hours later.

Bradley Wiggins, who has long been mentored by Sutton, pulled out of Thursday's pre-race media conference ahead of the Tour de Yorkshire, on his 36th birthday.

Team Sky rider Pete Kennaugh, who is competing in Yorkshire, issued an apology after criticising Olympic medallist Emma Pooley on Twitter.

Pooley questioned why Team Sky was established in 2010 to win the Tour de France, but there was no equivalent women's team to support her and others.

Kennaugh, who won London 2012 gold in the team pursuit, wrote on Twitter: "Emma pooley why would sky put money into the women's giro that aboslutely no one in the uk has absolutely no idea about

"Stop being so self centred and get over it."

His account appeared to be deleted, before being restored, with an apology.

"I've re-read the tweet i deleted and realise i came across like a total idiot im sorry to anyone i may have offended in how they were worded," he wrote.

Varnish, meanwhile, was training in Melbourne as she tried to keep her slim Olympic hopes alive.

The 25-year-old, who alleges Sutton told her to "go and have a baby" when dropping her from the Olympic team, posted a video on Twitter after travelling to Australia earlier this week.