Muawiyah Hassanien, head of the Emergency and Ambulance Department in the Palestinian Ministry of Health, on Friday said Israel last month began imposing restrictions on the transfer of patients with heart diseases and cancer to hospitals abroad.
"After mid-April we asked for permits to move 316 patients with serious illness and Israel approved only four cases," Hassanien said.
But the Israeli army disputed the figures, saying 184 requests had been received, of which 155 were approved since mid-April.
"Most of these Palestinian civilians receive medical treatment in Israeli hospitals," it said in a statement, adding that the rest of the requests were denied due to "security reasons."
Israel tightened its "closure" of Gaza following last month's assassination of top Hamas leader Abd al-Aziz al-Rantisi, fearing retaliation attacks by Palestinian groups.
Palestinian hospitals suffer a shortage of medical equipment and staff, especially cancer and heart disease specialists.
"We condemn Israel's slow death policy. Many patients could die if they are delayed in reaching hospitals abroad," Hassanien said.
He urged international human rights groups and the United Nations World Health Organisation to intervene to prevent what he described as "medical catastrophies" in Palestinian areas.