Assailants detonated a bomb outside a popular cafe in Gaza City early Sunday morning, apparently part of a campaign by shadowy extremists to eliminate perceived symbols of Western influence.

The pre-dawn blast smashed the cafe's windows and damaged its door. No one was hurt.

Cafe owner Khalid Harbid said another bomb went off outside his cafe last month. He charged that Gaza's Islamic Hamas rulers are not protecting his business.

"My cafe has become Sderot," Harbid said, referring to an Israeli town just outside Gaza that is the target of daily Palestinian rocket fire.

A Hamas official said police were investigating.

On Friday, assailants detonated a bomb outside a Christian school, causing no injuries. Over the past two years, extremists in Gaza have detonated bombs near cafes, hairdressers, record stores and institutions linked to the area's tiny Christian community, an apparent campaign to shut down Western-style or non-Islamic outlets.

Hamas, the armed Islamic group that rules Gaza, said it offers protection to institutions that ask for it.

At the same time, the Hamas regime is pursuing a policy of enforcing a strict Islamic moral code. The latest step is an attempt to block Internet websites Hamas considers unsuitable.

The Hamas information ministry said in a statement that it signed a deal with the Palestinian telecommunications company to start blocking "licentious websites" beginning May 15. So far, 5,000 websites have been blocked, said a senior telecom official, speaking on condition of anonymity because of the issue's sensitivity.

He did not list the sites.

The official said Hamas demanded all inappropriate sites be blocked. However, the telecom company cannot bring suitable equipment into the Gaza Strip to ban a large number of websites, the official said.

Israel tightly regulates equipment, fuel and commercial goods entering the Gaza Strip to pressure Palestinian fighters into halting their rocket fire at neighbouring Israeli communities.

In the past, unidentified assailants have planted bombs at the entrances of Internet cafes, accusing them in printed statements of allowing customers to view pornographic websites.

As of Sunday, Gaza residents could still view many pornographic websites.