Palestinian Authority Prime Minister Ismail Haniyeh has sent a series of letters to the kidnappers of a captured British journalist demanding his release, a top aide said Wednesday. Ahmed Youssef, an adviser to Haniyeh, said the letters have sought to "clarify to these people that this issue doesn't serve the interest of our people, and the Muslims." The comments confirmed that negotiations are under way to win the release of British Broadcasting Corp. correspondent Alan Johnston, who was kidnapped on March 12. "We are passing through a sensitive time," said Youssef. "We are trying to put some moral pressure on them." Youssef said the kidnappers had not demanded any ransom and suggested they were a militant Muslim group. "Money is not the issue. The issue is an incorrect understanding of Islam, how to deal with foreigners in general, an incorrect understanding of Islam among some," he said. Youssef declined to discuss the kidnappers' identities or ideology. "Any discussions about it will harm this issue," he said. Youssef said the prime minister's office believes Johnston was in good health, though they have not received firm evidence. A little-known group claimed to have killed Johnston in April, but provided no evidence of their claim. Top officials have since said the kidnappers have confirmed that Johnston remains in good health. Security officials earlier told AP that kidnappers were demanding millions of dollars in ransom and the release of an Iraqi woman Sajida al-Rishawi, 35, sentenced to death in Jordan for her role in the al-Qaida-led triple hotel bombing that killed 60 people there. Youssef declined to confirm whether the kidnappers had also demanded al-Rashawi's release. A security official, speaking on the condition of anonymity, because he is not authorized to speak to the press, said the demand to release Rishawi was a ploy to earn credentials among other extremist Muslims. Haniyeh's Hamas party, and the Fatah party of PA President Mahmoud Abbas don't want to compromise, fearing it will add to the chaos and lawlessness plaguing the Gaza Strip, he said. There has been string of kidnappings of foreign journalists over the past two years in Gaza. But most cases have ended within a day or two, and Johnston's captivity has dragged on far longer than anyone else. No one has been charged or arrested in previous kidnappings. Johnston, 44, was seized by Palestinian gunmen on March 12, and little has been reported about his whereabouts or condition.