Hackers assaulted the websites of mobile operators in the Czech Republic Thursday, the latest in a string of attacks this week which have also hit online media and banks.
The website of the Czech branch of Germany's T-Mobile was bombarded with traffic in a so-called DDOS (distributed denial of service) attack designed to overload networks.
The operator's spokeswoman, Martina Kemrova, said online services were made inaccessible to clients before being restored.
Telefonica Czech Republic said its website was also down for one hour, and that the attack appeared to come from Russia.
Hackers on Wednesday targeted the central bank CNB along with a number of commercial banks.