Users on Internet hosting company Fasthosts are claiming that their sites are being blocked by major ISPs including BT, Virgin, Orange and Karoo. The hosting company put out a statement saying that the site had had "DNS resolution issues" but won't clarify any further and the press office is not returning calls about the situation.

Although there are unconfirmed reports that the company has undergone a DDoS attack, Fasthost has denied this.

According to Fasthosts' customer Matt Houldsworth, writing on his Digital Quill blog, the problems has been going for three days already. "Fasthosts did have a message up on their status page about these problems, but this has now been taken down but my domain is still affected. I have messaged Fasthosts about these problems but have yet to get a response."

Houldsworth, who runs a series of affiliate sites, is looking for compensation for business lost while Fasthosts resolved the problem, He's also concerned that Fasthosts has not explained what the problem is "can you explain why we had this DNS issue? Just saying it is solved isn't good enough, is it going to happen again?," he posted on Twitter.

Fasthosts has suffered some problems in the past. Last year, in June and December, the company suffered repeated email outages and in 2008, the company was blamed for a variety of Internet problems after claims that its site was hacked and log-in credentials were stolen.