BRISBANE (Reuters) - British pop band Oasis wound up an Australian tour, plagued by reports of loutish behaviour, with an apology for bad singing. Their farewell concert in the northern city of Brisbane, which attracted only a few thousand fans, was marred by on-stage bickering among the band before it was cut short. "We're sorry about the singing," songwriter Noel Gallagher told the Seven television network. Some fans left before the concert finished. "It was actually quite boring," one unidentified fan told Seven. "It was just a waste of A$50 (US$33)," said another.