Four players with Portuguese top-flight club Rio Ave have been reportedly charged in a 500,000 euro ($597,000) match-fixing scam, local media revealed on Thursday.

The public prosecutor, when contacted by AFP, could not confirm the case which first surfaced on SIC television station and confirmed by the Correio da Manha newspaper.

According to the two media outlets the four unnamed players are suspected of taking bribes to fix a defeat for their team in a first division game against Feirense on February 6, 2017.

Rio Ave lost the match 2-1 on the way to finishing seventh in the end-of-season table.

Betting on the fixture had been suspended shortly before kick-off due to "the unusual volume of bets" placed on the encounter, Jogos Santa Casa, the monitoring body supervising betting in Portugal explained.

The total amount of bets placed on the game was in the region of half a million euros, media reported.

The club from Porto reacted "with surprise and indignation" at the news, stressing they had "no information" on any charges resulting from a fraud investigation.

After the suspension of betting on the game the police opened an inquiry "six months ago in which people connected to Rio Ave gave all the cooperation required of them", the club said in a statement.

The Portuguese League has reiterated "its total confidence" in all the teams engaged in the competitions it organises, and in particular in Rio Ave.