LONDON (Reuters) - Chris Froome will start his 2018 season as favorite for Spain’s Ruta del Sol on Wednesday, defying calls from senior figures in world cycling to withdraw from racing over the adverse drug test result he returned last September.

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The four-times Tour de France winner had twice the permissible amount of the asthma medication Salbutamol in his system after stage 18 of the Tour of Spain - a race he went on to win - but the Team Sky rider, who says he has done nothing wrong, did not receive a provisional suspension.

International Cycling Union president David Lappartient and rival riders Romain Bardet and Vincenzo Nibali have all said the British cyclist should cease racing until his case is resolved.

And pressure on Froome increased last weekend when Jonathan Vaughters, manager of the EF Education First - Drapac p/b Cannondale team, suggested the presence of the previous Ruta del Sol winner at the five-day event and other upcoming races will be “damaging to cycling”.

“The honorable thing would be to recuse yourself from racing until it’s resolved,” Vaughters told reporters at the Colombia Oro y Paz stage race last week.

But Froome and Team Sky remain intent on the 32-year-old riding out the controversy with a full racing program, including May’s Tour of Italy and July’s Tour de France.

Lappartient said last month that it could be “at least a year” before a ruling is reached.

“On balance I think it’s the right thing to do; for Chris to continue, and us to work in the background to support him and demonstrate there’s been no wrongdoing,” Team Sky principal Dave Brailsford told reporters in Colombia last week.

Team Sky’s stance will be vindicated if they can convince the UCI there was no wrongdoing on Froome’s part, but the risk of widespread damage to cycling should they fail is high.

Italian riders Alessandro Petacchi and Diego Ulissi received 12 and nine-month bans respectively for excess Salbutamol levels. Should Froome receive a similar, backdated ban, his results from last year’s Tour of Spain through to at least this year’s Tour of Italy would be scrapped.