* Fredericks faces probe over payment before Rio award
* Former sprint medallist denies any wrongdoing
* Steps down from evaluating Los Angeles and Paris bids
* FIBA's Baumann appointed to replace Fredericks (Updates with IOC reaction, Baumann's appointment)
By Karolos Grohmann
BERLIN, March 7 (Reuters) - International Olympic Committee member Frank Fredericks stepped down on Tuesday as head of the team evaluating bids to host the 2024 Olympics, as an IOC ethics commission investigates alleged payments to him before the awarding of the 2016 Games to Rio.
Namibian Fredericks, a four-time Olympic sprint silver medallist over 100 and 200 metres, denied any wrongdoing and said he was moving aside so as not to be a distraction in the investigation, which was launched last Friday.
On Monday he stepped down as head of a task force at the international athletics' federation (IAAF).
"I categorically deny any direct or indirect involvement in any untoward conduct and confirm that I have never breached any law, regulation or rule of ethics in respect of any IOC election process," Fredericks said in a statement.
As head of the IOC bid commission, he had been due to lead an inspection visit to 2024 candidate cities Los Angeles and Paris in April and May and draft a report.
Fredericks said he would not now attend a July briefing for IOC members on the 2024 bids, and would not take part in voting for the host city, due to take place in Peru in September.
The IOC said it accepted his decision to step aside and appointed Patrick Baumann, secretary general of international basketball federation FIBA, as the new bid commission head.
The IOC said its ethics commission had recommended that Fredericks be removed from his positions both within the organisation and the 2024 bid process.
"In line with the IOC ethics commission, the IOC Executive Board recalls the importance of respecting the principle of the presumption of innocence. It also notes Mr Fredericks’ categorical rejection of the allegations made against him, the IOC said.
Its probe followed a report by French newspaper Le Monde that prosecutors were investigating payments made shortly before the vote in 2009 that awarded the 2016 Olympics to Rio.
The paper said Papa Massata Diack, the Senegalese son of disgraced former IAAF President Lamine Diack, transferred about $300,000 to a company linked to Fredericks.
Fredericks told Le Monde the money was paid for work he did to promote athletics in Africa at the time.
The elder Diack is under investigation in France for corruption, while the son is the subject of an Interpol wanted notice, issued at the request of French authorities, for alleged corruption and money laundering. Papa Diack has denied the allegations and said both he and his father are innocent.
Fredericks added in his statement on Tuesday: "I believe in the integrity of the election processes of the IOC and never noticed anything untoward to make me doubt this. I reiterate that I was never involved with any vote manipulation or for that matter any other inappropriate or illegal practice.
"Nonetheless I have personally decided... I step aside as chairperson of the 2024 evaluation commission, because it is essential that the important work my colleagues are doing is seen as being carried out in a truthful and fair manner." (Reporting by Karolos Grohmann; Editing by Mark Trevelyan and Ken Ferris)