JAKARTA - The second biggest city in Indonesia has blocked local government employees from using three social networking services, including Facebook, due to a decline in productivity, officials said Wednesday.

The Surabaya administration has blocked access to Facebook, Friendster and instant messaging tool Yahoo! Messenger during office hours since Monday.

"In order to increase the concentration of the civil servants, the mayor had to block those three social networking sites during office hours, starting from 8:00 am to 4:00 pm," administration spokesman Chalid Buchari said.

He said the ban was introduced because many civil servants wasted too much time on the services during office hours.

"We're still evaluating the idea that we should block Facebook permanently in all levels of government," Buchari said.

The administration, however, still approved the use of Internet search engines, such as Yahoo! and Google, to access news and information.

In May, a meeting of hundreds of Islamic scholars from Java and Bali islands warned that using social networking sites such as Facebook could lead to pornography and "obscenity."