Repeated attacks by Saudi Arabian hackers on Israeli websites and the hacking of Israeli credit-card details has led to a series of tit-for-tat attacks.

The round of cyberwarfare began two and a half weeks ago when a Saudi hacker with the web nickname 0XOmar posted 15,000 Israeli credit-card numbers and passwords. 0XOmar and his allies have since posted thousands more Israeli credit details and, on Monday, attacked the websites of Israeli airline El Al and the Tel Aviv Stock Exchange, forcing them to suspend service for hours.

On Tuesday, Israeli hackers fought back when a group calling itself IDF-Team forced down the website of the Saudi Stock Exchange and other financial websites in the Gulf region. Three other groups of Israeli hackers posted online credit-card details, emails and Facebook accounts of Saudi and other Arab nations' citizens. IDF-Team posted on a web-forum: "We are not afraid to fight back" and promised that it would continue attacking Saudi and other Arab websites if the attacks on Israeli websites and users continued.

"Israel has incredible cyber capabilities," said one senior official, "but they are used to protect the defence establishment and vital national infrastructure. The government has still not realised that, in the realm of cyberwarfare, ordinary civilians who conduct their personal and financial affairs on the web are also vulnerable."

Mr Netanyahu announced last May that a special task force would be set up to co-ordinate cyber-defence efforts, but so far no budgets have been allocated. A director was appointed only a month ago and has not yet started hiring staff.

A government technology expert said: "Four different agencies are now involved in cyber-defence and this new task force is only making things more complicated. The government hasn't even decided what its responsibilities will be."