The World Anti-Doping Agency (WADA) has backed the UCI's decision to clear Chris Froome of any wrongdoing following a lengthy anti-doping investigation.

The UCI confirmed on Monday that proceedings against the four-time Tour de France winner had been officially closed - just five days before the start of this year's race - after the Team Sky rider tested positive for excess levels of asthma drug salbutamol at the 2017 Vuelta a Espana.

WADA issued guidance to the UCI in helping them make their decision, although the anti-doping body have confirmed that their advice was primarily the result of being unable to compare the sample with a controlled study in what was a "complex" case.

A statement from WADA read: "WADA's decision follows a full and careful review of all explanations and supporting evidence submitted by Mr. Froome in the month of June (which the UCI shared with WADA), as well as thorough consultation with internal and independent external experts.

"On the basis of this, WADA’s position is as follows:

"Based on a number of factors that are specific to the case of Mr. Froome, WADA concluded that the sample result was not inconsistent with the ingestion of inhaled salbutamol within the permitted maximum dose.

"WADA recognises that, in rare cases, athletes may exceed the decision limit concentration (of 1200 ng of salbutamol per ml of urine) without exceeding the maximum inhaled dose. This is precisely why the Prohibited List allows for athletes that exceed the decision limit to demonstrate, typically through a controlled pharmacokinetic study (CPKS) as permitted by the Prohibited List, that the relevant concentration is compatible with a permissible, inhaled dose.

"In Mr. Froome's case, WADA accepts that a CPKS would not have been practicable, as it would not have been possible to adequately recreate the unique circumstances that preceded the September 7 doping control (e.g. illness, use of medication, chronic use of salbutamol at varying doses over the course of weeks of high intensity competition).

"Therefore, having carefully reviewed Mr. Froome's explanations and taking into account the unique circumstances of his case, WADA accepts that:

"The sample result is not inconsistent with an ingestion of salbutamol within the permitted maximum inhaled dose;

"An adequate CPKS is not practicable; and the sample may be considered not to be an AAF.

"WADA believes this to be the right and fair outcome for what was a very complex case."