MADRID (AFP) - Mexican rockers-with-a-conscience band Mana derided Friday the decision by the United States to build a 1,200 kilometre (745-mile) fence along the US-Mexico frontier by descending from a makeshift wall on to the stage of a concert in Madrid.

Mana, playing the Spanish capital's Las Ventas bullring for a second straight sellout night to some 20,000 fans, have spoken out in recent months against the barrier, accusing the US government of hypocrisy for allowing its construction after condemning the old Berlin Wall.

The band performed their wall stunt and then pointedly began their show with a track entitled "Dejame entrar" (Let me in).

Mana, who merge hard rock with Latin and reggae-influenced ballads and have a major following in the Hispanic community in the United States, won a Grammy award this year for Best Latin Rock/Alternative Album for their 2006 album "Amar es Combatir" (to love is to fight).

While much of their work over three decades has comprised dreamy ballads with a rocking twist their work equally focuses on social issues.

Vocalist Fher opened the Madrid concert with a song praising "women who have sun in their gaze and also to those who carry life inside," an apparent reference to the recent debate in Mexico over controversial moves to decriminalise abortion.

Mexico City legislators recently voted to legalise abortion, previously illegal in most cases save for cases of rape, severe birth defects or if the woman's life is at risk, but the move sparked protests among conservatives in the predominantly Catholic country.