BUENOS AIRES, Argentina (AP) — In a sign of increasing tension ahead of October elections, the top presidential candidates in Argentina and other government officials exchanged accusations on Tuesday after protests over alleged vote fraud in a northern province were broken up with tear gas and rubber bullets.

Cabinet chief Anibal Fernandez suggested that foreign elements from "up north" had organized the late Monday protests, which ended when police fired on people and forcefully removed them from the main square of San Miguel de Tucuman, about 807 miles (1,300 kilometers) north of Buenos Aires.

Mauricio Macri, the leading opposition candidate for October's presidential election, told reporters on Tuesday that it's impossible to say Sunday's gubernatorial election in Tucuman was clean when at least 40 ballot boxes had been burned.

"We can't say that this was a normal election," said Macri, adding that having voting irregularities "in the 21st century is unacceptable."

Ruling party presidential candidate Daniel Scioli said that complaining protesters and politicians simply didn't want to accept that ruling party candidate Juan Manzur won the election. Scioli accused Macri of stirring up emotions.

"I understand (Macri) is in a presidential campaign but he has a responsibility," to project calm and respect voters' wishes.

Sergio Massa, a former ruling party loyalist who broke to run on his own ticket, said the incident showed it was time to modernize the national voting system, which for federal elections still uses paper ballots.

It's time "to reform this outdated, obsolete and old system," said Massa.

According to results released Monday, Manzur won with 54 percent of the vote compared to 40 percent for Jose Cano, the closest contender.

Demonstrators claimed fraud in the provincial governor's race after several ballot boxes were burned in incidents that authorities have said were instigated by people of several political parties.

Cabinet chief Fernandez initially told reporters that he didn't know what happened in Tucuman because he "was sleeping" when the incident happened. Later in the day, he suggested that the skirmishes were "actions of the North that seek to delegitimize the elections" later this year.

Administration officials from the ruling party, in power since 2003, periodically complain of meddling by foreign countries.

Outgoing governor Jose Alperovich said police force was "excessive" and that prosecutors would investigate. He also promised to open "ballot box after ballot box" if a recount is necessary.

Electoral authorities have said the burnt ballot boxes represented only a fraction of the total votes, and including their ballots would not the outcome.

___________

Follow Peter Prengaman: http://twitter.com/peterprengaman