Pop stars One Direction have apologized to fans after a sales website crashed as fans rushed to scoop up bargain price $13 tickets to the band's show in Italy.

The Best Song Ever hitmakers are set to perform two concerts in Milan over the weekend (28-29Jun14), and they thrilled devotees by announcing plans to slash some ticket prices for the Saturday night (28Jun14) show.

The bargain seats at the Stadio San Siro have a restricted view, but fans flooded an Italian sales website in a bid to get their hands on the cheap tickets, crashing the online portal and prompting an apology from One Direction's Niall Horan, who writes in a post on Twitter.com, "Sorry to all those who tried to buy the new 10 Euro tickets for tonight. The site crashed! But it's back up and running."

The gig will be filmed for a concert DVD and Horan revealed the special ticket scheme was introduced to make sure the venue is packed out.

He previously explained, "Milan! Filming our DVD... at San Siro! Tickets have been sold out for a year but we're releasing a few more restricted view seats... Want as many of u guys 2 (to) come & be part of it... A few restricted view tkts (tickets) will go on sale for 10 Euros!... Milan you are gona (gonna) be watch (sic) from all over the world! You gotta be loud, crazy."