Biffy Clyro's current US tour has been affected by visa problems.

The band were due to begin the tour at Great Scott in Boston last night (September 13), but only singer Simon Neil was able to make the trip due to immigration delays.

As a result, Neil performed several songs acoustically for fans, who were allowed into the show for free.

In a statement, the band said: "The members of Biffy Clyro sincerely apologise to everyone for this unforeseen occurrence."

Biffy Clyro's tour is due to continue across the US as scheduled before they play a series of UK arena dates at the end of 2010.

The Scottish band recently promised to release a new album in 2011.

(by Jason Gregory)