Lance Armstrong stepped down as chairman of his Livestrong cancer charity on Wednesday as Nike broke all ties with the disgraced cycling star over “seemingly insurmountable evidence” of doping.

Both developments came as the International Cycling Union (UCI) faced growing pressure to reveal how the 41-year-old, seven-time Tour de France champion had been able to escape detection for doping for so long.

In a statement, cancer survivor Armstrong said he would “conclude my chairmanship to spare the foundation any negative effects as a result of controversy surrounding my cycling career.

Separately, sportswear giant Nike a major sponsor that had stuck firmly by Armstrong for months in the face of doping allegations issued a statement that accused him of years of deception.

“Due to the seemingly insurmountable evidence that Lance Armstrong participated in doping and misled Nike for more than a decade, it is with great sadness that we have terminated our contract with him,” it said.

It added “Nike plans to continue support of the Livestrong initiatives created to unite, inspire and empower people affected by cancer.”

Livestrong is one of the best-known cancer charities in the United States, having raised nearly $500 million since it was founded by Armstrong in 1997 as he recovered from testicular cancer.

Its iconic yellow wristband was launched in 2004 in collaboration with Nike.

Armstrong always maintained he did not use banned substances, but in August he chose not to contest charges put forward by the US Anti-doping Agency (USADA) that he was a serial drugs cheat.