RIO DE JANEIRO, April 22 (Reuters) - Sao Paulo coach Muricy Ramalho has rubbished suggestions that his own club was behind an incident on Sunday, when their changing room filled with a mysterious spray at half-time in a derby match at Palmeiras. As the row over the incident continued, police also visited Palmeiras's Parque Antartica stadium while Sao Paulo sent an official protest to a disciplinary tribunal, demanding their opponents be given a home ban. Sao Paulo fled the changing room, saying the unidentified substance had caused irritation to their eyes and nostrils. Palmeiras won the Paulista championship game 2-0. Palmeiras coach Vanderlei Luxemburgo later insinuated that Sao Paulo might have been behind the incident, apparently to in a bid to discredit Palmeiras's stadium. But this was refuted by Ramalho on Tuesday. 'Luxemburgo distrusts a big club like Sao Paulo and it means he also distrusts me,' Ramalho told a news conference. 'But how am I going to spray gas at myself? 'It was a very serious incident. If I had been trying to pull a fast one, then I would have taken the team off the pitch at halftime and abandoned the game. 'I hope he regrets his comments.' A police official who inspected the changing room confirmed on Tuesday that it had been filled with the substance but could not say how. 'It was detected that there really had been a gas in the area,' he told the Sportv cable channel. 'It wasn't pepper spray. It was a gas which provokes irritation in the respiratory system. 'We can't discover how it got in there. I can only say that there was gas inside.'