Riot police in a northern Argentine province have fired tear gas and rubber bullets to break up hundreds of protesters claiming fraud in an election for governor.

Local station TN showed police firing on crowds late on Monday in the main square of San Miguel de Tucuman.

Some protesters were seen with bloodied faces and large welts on their necks.

Videos and photos posted on social media also appeared to show protesters throwing small objects at riot police.

Attempts to reach police in the northern Tucuman province were not successful and it was not immediately clear how many people had been injured.

Protesters claimed fraud took place in Sunday's governor's race, won by Juan Manzur from the country's ruling party.

Mauricio Macri, the leading opposition candidate for October's presidential election, also said he believed fraud had been committed.

Ruling party presidential candidate Daniel Scioli said that complaining protesters and politicians simply did not want to accept that Manzur won the election.

Accusing Macri of stirring up emotions, Scioli said: "I understand [Macri] is in a presidential campaign but he has a responsibility," to project calm and respect voters' wishes.

Así fue El momento de mayor furia #TucumanElige pic.twitter.com/mmL9bTJOxm

— Miguel Velárdez (@miguelvelardez) August 25, 2015