A cyber-jihad has erupted between groups of rival Islamic hackers in Bangladesh and Indonesia, resulting in attacks on hundreds of sites.

The rival hackers have abandoned their normal pursuit of Israeli targets and have instead turned on each other. It is unclear which side started the war, although the Bangladeshi group have accused Indonesia of supporting Israel, even though relations between the two countries are frosty at best.

A group called Bangladesh Grey Hat Hackers claimed to have hacked around 900 Indonesian sites and threatened to expand their assault to include ecommerce and financial sites. The full list also includes pet food sites, foreign embassies, and government websites. At the time of writing, loading up many of the sites resulted in a 404 error.

On the group's Facebook page, a hacker called Rotating Rotor wrote an open letter to Indonesia, which we've rewritten slightly for the sake of clarity.

Earlier today, Rotor wrote: "Assalamu Alaikum. First of all take my greetings of Ramadan. As you all know we are in a cyber war with the hackers of your country. You guys only knew that we are defacing your countries sites.

"Now you can ask if we don't deface Muslim's sites then why we are attacking Indonesian sites? Believe me. We are forced to do so with your hacking teams, who wanted war with us several times before."

The group have some "simple demands" which they have not yet announced. If these are not met, the hacking will continue for another six months, the group threatened. It claimed that five groups of Indonesians had carried out small-scale cyber attacks in recent months, eventually provoking a full-scale retaliation, despite repeated calls for peace.

Rotor added: "We are getting thousands of requests from many Indonesian's to stop the attack. We feel hurt after seeing this. We decided to stop. But Indo Hackers defaced our sites again. Then we changed our mind and continue to attack.

"Right now we are just only defacing. If your Hackers don't stop we are going to inject malware and viruses to all of your e-commerce sites and destroy your e-commerce system.

"We already gain access to many of your servers, We just observing your Hackers activities.

"Believe me, I swear. We have the capabilities to continue this war for minimum 6 months. We got access to your unlimited servers."

On the page, there are also dozens of comments from people using the famous Anonymous Guy Fawkes mask as their profile picture.

One wrote: "The Zionists are laughing at us. Muslim vs Muslim. Better we all unite, not fight each other."

Indonesian hackers also released a list of the Bangladeshi sites they have attacked in turn, which include religious courts and government websites, including the Presidential page.

We visited some of the sites on the list, which show a message that said: "Stop attack my country. Don't touch my country Bangladesh. Fuck BD Gay Hay UR lamer. A little dog Murkho Manob was using message slander. Bitch dog really. YOUR MOTHER FUCKER!"

Murkho Manob is a Bangladeshi hacker who targets websites he claims support Israel. A quick Google search shows he has attacked the website of a British Thai boxing club and also a rather quaint-looking hotel, as well as Israeli websites.

We have written to both sides for comment, but they have not yet replied. ®