A Belgium fan drinks beer as he waits for the start of the Group H match between Belgium and Russia at the Maracana Stadium in Rio de Janeiro during the 2014 FIFA World Cup on June 22, 2014. Photo: AFP

It has been a common sight at World Cup games: huge lines of fans buying beer inside stadiums before ­returning home with stacks of empty souvenir cups in their hands.

A top FIFA official expressed concern at the amount of drinking during the month-long tournament, though it was soccer's world governing body that forced Brazil to change its laws to allow beer sales at stadiums.

Brazil outlawed alcohol at games in 2003 to curb fan violence, but it had to pass a special law authorizing booze at the World Cup as part of its agreement to host it.

In the corridors of the 12 World Cup arenas, fans lined up to buy US-made Budweiser or the local Brahma brand, both owned by Belgian-­Brazilian giant Anheuser-Busch InBev, a major tournament sponsor.

Many fans have streamed out of stadiums with handfuls of the 473-milliliter commemorative cups in their hands. They paid 13 reals ($6) for a Budweiser, or 10 reals for a Brahma, and the cups have become hot items for sale online.

But AFP reporters saw some ­heated arguments, including a brawl, during two games at Rio's Maracana Stadium involving fans who had apparently consumed ­alcohol.

At the Uruguay-Colombia last-16 game on June 28, several Brazilian fans traded blows with Uruguayans in the stadium's corridor.

The fight began after an appa­rently inebriated Brazilian man shouted in the face of a Uruguayan woman to mock her team's defeat, which made her drop her beer, prompting a countryman to come to her defense.

After the France-Germany quarterfinal on Friday, security guards had to get between two men wearing jerseys of rival Sao Paulo soccer clubs in the corridor of the Maracana.

The man in the Corinthians shirt, holding around eight empty cups in one hand, shouted "come here" at the other one, but guards were able to keep them separated.

During the game, several security guards took positions between fans screaming at each other.

Some Brazilians were glad they could drink during World Cup games but they backed the prohibition during domestic league games, saying local fans can get violent.

"People don't know how to drink with moderation," said Carlos Franca, a 48-year-old Brazilian with a yellow and green top hat who had a couple of beers during France-Germany.

Diogo Albuquerque, a 33-year-old engineer bedecked in Brazil team ­colors, said the difference with domestic matches is that "there's a lot of security" at World Cup games.

A Brazilian couple who attended Argentina-Belgium in Brasilia said they saw several drunk people at the game.

"It's much better to see a game with a beer at the stadium, but it can lead to fights. It has its positive and negative sides," said Jaroslav Duchicry Junior, 30.

FIFA Secretary-General Jerome Valcke said last week he was "struck and worried by the level of drunkenness of many supporters who do not behave well."

He warned consumption controls could be imposed, but no such measures appear to have been ordered.

A spokeswoman for AB InBev in Brazil, Daiana Rodriguez, told AFP that beer would continue to be sold normally because FIFA has not required controls.

"This [control] would depend on FIFA," she said. The brewer "will continue selling beer until the last game."

Another AB InBev spokeswoman said the company provided "responsible server training" for stadium staff. The company could not provide World Cup sales figures.

The cups, meanwhile, have ­become hot collector items for sale online.

The red Brahma cups had the names of teams, their flags and the date of the game during the group phase. Only the name of stadiums and date appeared in the quarter­finals.

On a Brazilian personal advertisement website, one person asks for as much as 50 reals for one red Brahma cup from a last-16 game. Another asks 30 reals for a golden Budweiser cup that has an image of the World Cup's trophy.

Rafael Dottore, a 33-year-old management consultant, came out of France-Germany with three empty cups as keepsakes.

While the beer costs more than what Brazilians would normally pay for a pint, he said "they would pay in a World Cup stadium. It's a souvenir."