* Erdogan has said will "wipe out" Twitter
* US calls ban anti-democratic
* DNS numbers, used to get round ban, no longer working
By Daren Butler
ISTANBUL, March 22 (Reuters) - Turks faced fresh difficulties in accessing the Internet on Saturday after the government blocked access to Twitter, the site where tweets on a corruption scandal have angered Prime Minister Tayyip Erdogan.
Twitter was blocked late on Thursday, hours after Erdogan vowed to "wipe out" the social media service. Leading international condemnation, the White House said the Twitter ban undermined democracy and free speech.
Turks attempting to access Twitter have found an Internet page carrying court rulings saying that a "protection measure" has been taken, blocking the site.
But many have been able to get around the ban, either by using virtual private network (VPN) software or changing their Domain Name System (DNS) setting, effectively disguising their computers' geographical whereabouts.
By Saturday, though, computers that had been set with DNS numbers widely circulated to help people get around the ban were not able to access the Internet at all.
"Apparently alternate DNS servers are also blocked in Turkey. New settings are being circulated," wrote one Twitter user.
There was no immediate official comment.
Erdogan, who is campaigning for his party in local elections on March 30, did not talk about the Twitter block at rallies on Friday. He was due to continue campaigning on Saturday in the southern province of Hatay and in the capital Ankara.
Industry Minister Fikri Isik said on Friday talks with Twitter were taking place and the ban would be lifted if the San Francisco-based firm appointed a representative in Turkey and agreed to block specific content when requested by Turkish courts.
The company said in a subsequent tweet: "We stand with our users in Turkey who rely on Twitter as a vital communications platform. We hope to have full access returned soon."
A company spokesman declined to say whether it would appoint someone in Turkey but said it was moving forward in talks with the government. (Editing by Robin Pomeroy)