Israel is holding two Palestinian mothers suspected of planning to carry out a twin suicide bombing. The Shin Bet announced Wednesday it arrested a pregnant Palestinian mother of eight and her niece, herself a mother of four, after they tried to cross into Israel from the Gaza Strip on May 20. The women, who were detained on an intelligence tip-off, told Shin Bet interrogators that they had been recruited by Islamic Jihad to blow themselves up in Israel. They had received entry permits on humanitarian grounds, citing a bogus medical complaint that required advanced hospital care, and were to have traveled to the West Bank to be outfitted with bomb belts. Islamic Jihad had no immediate comment.