By Catarina Demony and Sergio Goncalves
LISBON (Reuters) -Portugal's biggest football club Benfica said on Wednesday their president Luis Filipe Vieira was detained as part of an investigation into alleged tax fraud and money laundering, raising questions about his future at the helm.
Without naming Vieira, the public prosecutors' office said in a statement that a sports' executive and three others were detained over deals worth more than 100 million euros ($118 million) that may have caused large losses to the state and several companies.
Benfica said Vieira was being held for questioning, adding that although the investigation did not involve the club itself, they were collaborating with relevant authorities.
The prosecutors' office alleged that offences including fraud, money laundering and forgery had been committed since 2014, and said those arrested would appear before a judge on Thursday.
Public broadcaster RTP and other local media said Vieira's business partner Jose Antonio dos Santos was also detained. Antonio dos Santos is the largest individual shareholder of Benfica SAD, a listed company on the Portuguese stock exchange that manages the professional football team.
Club officials scheduled an emergency meeting following Vieira's arrest, RTP said. Benfica did not reply to a request for comment to confirm the meeting was taking place.
Earlier on Wednesday, more than 100 inspectors in Lisbon and elsewhere raided homes, lawyers' offices, the company's headquarters and a bank.
Newspaper Sol said the investigation was related to loans granted by Portuguese lender Novo Banco to Vieira's business group as well as to the sale of shares in Benfica SAD.
A parliamentary inquiry into Novo Banco found Vieira's business group owed the bank around 400 million euros. Portugal's Resolution Fund owns 25% of Novo Banco.
Benfica is Portugal's most popular club by membership and Vieira was recently reelected for another fours years at the club's helm.
Benfica SAD shares dropped 5.52% following the news.
($1 = 0.8475 euros)
(Reporting by Catarina Demony and Sergio Goncalves; Editing by Toby Davis)