Red Bull are investigating a complaint against their Formula One team boss Christian Horner, the Austrian energy drink company said in a statement on Monday without giving any details about the allegations.
The Briton presided over the most dominant season in Formula One history last year, with Max Verstappen taking his third title in a row and the team winning 21 of 22 races.
"After being made aware of certain recent allegations, the company launched an independent investigation," Red Bull said.
"This process, which is already under way, is being carried out by an external specialist barrister. The company takes these matters extremely seriously and the investigation will be completed as soon as practically possible.
"It would not be appropriate to comment further at this time."
The Times newspaper reported Horner, 50, had been accused of inappropriate behaviour by a female colleague, who complained to the team's parent company.
There was no comment from the team but Horner, who is married to former Spice Girls singer Geri Halliwell, told Dutch newspaper De Telegraaf that he completely denied the allegations.
Carlos Alcaraz will miss the Madrid Open for the second consecutive year after withdrawing on Friday with a wrist injury, dealing another blow to the world number two's clay court preparations ahead of his French Open title defence.
Novak Djokovic is still working through the injury problems that forced him to miss recent tournaments in Miami and Monte Carlo and said on Friday that he will not feature at next week's Madrid Open, one of the last stops before the French Open.
Mumbai Indians head coach Mahela Jayawardene has defended Jasprit Bumrah after the struggling pace spearhead went a fifth Indian Premier League match without a wicket in Thursday's seven-wicket defeat by Punjab Kings.
Iranian women's football players Fatemeh Pasandideh and Atefeh Ramezanisadeh thanked the Australian government on Friday for offering a "safe haven" and said they wished to resume their sporting careers after rebuilding their lives.
Ollie Watkins still has hope of making England's World Cup squad despite being dropped for last month's friendlies against Uruguay and Japan, with the Aston Villa forward saying all he can do in the last few weeks of the season is score goals.
Dubai Police, in collaboration with the UAE Ministry of Interior, have arrested an Irish fugitive accused of involvement in an organised criminal group linked to international crimes in his home country.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan has met with His Highness Sheikh Hamad bin Mohammed Al Sharqi, Supreme Council Member and Ruler of Fujairah, to discuss national priorities and the country’s continued development.