Surabaya, Indonesia  - The mayor of Indonesia's second largest city, Surabaya, has banned civil servants from accessing popular social networking site Facebook during work hours, an official said Tuesday.

Hundreds of employees working at the municipal office accessed Facebook from government computers everyday, slowing the local internet network and making them less-focused on work, city spokesman Chalid Buchari said.

The ban also applies to rival networking site Friendster and the Yahoo Messenger messaging service.

"The mayor will not prevent people from obtaining information and expressing their opinions online, but to improve the civil service work concentration, the mayor decided to block the three websites from 8 am to 6 pm," Buchari said.

A city employee who declined to be identified said he and his colleagues could still access Facebook and other sites from Blackberrys and other mobile devices.

"Social networking sites are useful. I can't deny that there are colleagues who sit at their desks Facebooking all day," he said.

The site is extremely popular in Indonesia, as more people gain access to the internet with cheaper connection costs and hardware.

According to website tracker Alexa, Indonesia ranks fifth in the number of Facebook users, after the United States, the United Kingdom, France and Italy. (dpa)