Gerard Pique (right) and Alex Song seem to be fighting on top of the Barcelona bus. [Photo: Daily Mail]

Barcelona stars Gerard Pique and Alex Song appeared to have been scrapping while on top of the team's double-decker bus to celebrate their La Liga triumph, Daily Mail reports.

Pictures captured showed, former Arsenal midfielder Song and Pique seemed to be fighting while the bus made its way around the Catalan city while Carles Puyol and goalkeeper Victor Valdes looked to be intervening.

At one point, Song was seen grabbing Pique's arm and cocking his clenched fist as if readying himself to throw a punch at the Spain defender.

The bus tour was an unruly affair with video footage emerging of the players drinking and partying as the bus travelled around the city and police picking up empty bottles from the streets.

There was a possibility that the superstars were simply joking about as footage showed how the bus parade turned into a party with plenty of beer-drinking on show from the Spanish champions.

But based on the images, the pair looked to be seriously quarrelling atop the train. Although the scuffle went unnoticed on Monday afternoon, politicians in Catalonia have complained that drinking on the bus was setting a bad example to young fans who watched their title-winners parade the trophy.

The parade was to honour Barca reclaiming their La Liga crown from Real Madrid, after mounting a 10-point lead with three games to play.

Barcelona held their end-of-season awards dinner last night, and Song, who left Arsenal for Spain last summer did not appear in any of the pictures released.

- Adapted from Daily Mail