Irish rock megastars U2 have postponed one of their two concerts in Spain next month due to a general strike called by the country's unions on the same day, the band announced.

"Due to the scheduled general strike in Spain, on September 29th, U2 promoters have today announced that the date for the U2 concert in Seville, currently set for that same day will be postponed to September 30th," the band said on its website, www.u2.com.

"Although the specifics of the strike have not been announced, in the past the strike has affected security services, public transportation, cleaning as well as medical and hospital services which are all integral to the running of the concert."

It said fans who had bought tickets but were unable to attend the rescheduled performance could obtain refunds by September 10.

The band, which launched the second part of its "360 degrees" tour in Turin on August 6, is also scheduled to play in the northern Spanish city of San Sebastian on September 26.

The tour, which began in Barcelona in June of last year, is to conclude in the United States in July 2011.

The 16 North American shows were initially planned for this year but were rescheduled for 2011 after lead singer Bono underwent emergency surgery on his back in Germany in May.

U2, founded in Dublin in 1978, has sold around 100 million albums.

The band's last tour in 2005 and 2006 drew some 4.5 million fans at 127 shows, all sold out.

Spanish unions called a general strike for September 29 to protest the socialist government's planned labour market reforms that would make it easier to hire and fire workers.