EXTRA day tickets for the Sonisphere rock festival at Knebworth House next month have gone on sale.

Organisers have increased capacity at the Hertfordshire stately home to enable more festival-goers to enjoy the event running from Friday, July 8 to Sunday, July 10.

A statement released by promoters said: “After a fantastic response to the day ticket ‘Power Ballot’ scheme launched by organisers last month, Sonisphere Festival has successfully applied for increased capacity for the 2011 event at Knebworth, and has received approval to release more tickets.”

Due to space restrictions on the campsite, the increased capacity does not allow for additional weekend/camping tickets to be made available, but an extra allocation of single day tickets are on sale now.

Day tickets are priced at �80 plus booking fee and are available from the Sonisphere website – see link above right.

Organisers added: “With weekend camping tickets nearly sold out, those wishing to come and enjoy the full weekend and all Sonisphere has to offer are advised to secure their tickets quickly.”

The opening day of the festival will be headline by thrash metal’s Big 4 of Metallica, Slayer, Megadeth and Anthrax.

Scottish rockers Biffy Clyro top the bill on the Saturday, with American metallers Slipknot closing things on the main stage the following night.

* See this week’s Welwyn Hatfield Times, out Wednesday, for the first of our festival previews.