By Alan Philps in Jerusalem www.telegraph.co.uk

Shin Bet, the Israeli security service, was covered in embarrassment yesterday after falsely accusing a Jewish woman of helping a Palestinian suicide bomber who blew himself up in Rishon Lezion, killing two people.

The security service announced on Friday that the bomber had been driven to his target by a Palestinian man, Ibrahim Sarahna, 33, and his Jewish wife, Marina Pinsky, 26, who immigrated from Russia 11 years ago.

In what was seen as a major intelligence coup, the couple were arrested during a shopping trip the day after the bomb. The Israeli press greeted the news with warnings about the dangers of mixed marriages.

No one was more surprised to hear of the case than Mrs Pinsky, who appeared on television at the weekend to deny that she was in prison or involved in the bombing.

The security service discovered that the woman held in custody for more than a week was in fact Irina Polyachek, a Ukrainian Christian described as a former prostitute.

It emerges that there are two Palestinian men called Ibrahim Sharahna, distant cousins, both of whom married women from the former Soviet Union.

The Ibrahim Sharahna who is the suspect in this case lived in a Palestinian refugee camp near Bethlehem with his wife Irina. She was using a false Israeli identity card in the name of Mrs Pinsky.

The real Mrs Pinsky was briefly married to another Ibrahim Sharahna, but the union broke up. When she heard on the radio that she and her ex-husband were terrorists, she barricaded herself in her home with her daughter.