MAPUTO (Reuters) - Thousands of people fleeing an attack claimed by Islamic State have made their way to safety elsewhere in northern Mozambique, aid workers said, while a small group of victims arrived by boat in neighbouring Tanzania.Insurgents hit the coastal town of Palma, adjacent to gas projects worth $60 billion, with a three-pronged attack last Wednesday. Fighting continued as recently as Tuesday, security sources involved in rescue efforts and the United Nations said. Reuters has not been able to independently verify the accounts from Palma. Most communications to the town were cut last Wednesday. A U.N. spokesman said that so far 5,300 displaced people had been registered in different districts of the Cabo Delgado province, home since 2017 to a simmering Islamist insurgency linked to Islamic State. Numbers of the displaced were expected to rise in the coming days. Since Tuesday, more than 300 survivors of the attack had arrived in provincial capital Pemba by plane and boat, a senior humanitarian official based in Mozambique told Reuters. A boat carrying another 1,000 people, including some injured, was expected to arrive in Pemba late on Wednesday after its departure from a gas project site near Palma was delayed, three people briefed on the rescue operation said. In the village of Kilambo across the border in Tanzania, another boat with 45 people on board docked on Tuesday afternoon, a local community leader told Reuters, adding the people had been given food and shelter. Others seeking shelter in Tanzania had failed to cross the border because of a difficult river crossing, U.N. humanitarian officials said. Tanzanian government and border officials did not respond to requests for comment. The attack probably displaced tens of thousands of people, aid groups said, with people scattering into dense forest or attempting escape by sea. Mozambique’s government has confirmed dozens of deaths, including at least seven killed when militants ambushed a convoy of vehicles trying to escape a besieged hotel. Witnesses have described bodies in the streets, some of them beheaded. Phone calls to Mozambique’s government and security officials went unanswered on Wednesday. President Filipe Nyusi said at an event unrelated to the Palma attack on Wednesday that the government will approach the enemy with “forcefulness”, describing the attack as not the biggest the country had seen. (GRAPHIC: Militant attack in northern Mozambique - ) Dollar-denominated bonds issued by Mozambique’s government have come under pressure since the fighting escalated a week ago, losing more than 3 cents in the dollar to trade as low as 81.75 cents, their lowest level since October 2020. Islamic State claimed the attack on Monday via its Amaq news agency. A U.S. official said it may show the group’s increasing “brazenness” in Mozambique, where militants are now seeking to hold towns. The Soufan Center, a U.S.-based security-focused think tank, said the latest attack could prompt greater overseas intervention in Mozambique, as the government was unable to contain the insurgency. U.S. army special forces are already in Mozambique, and French troops have been monitoring the escalating violence from the nearby French island of Mayotte, it noted. Portugal is preparing to send a small contingent of soldiers to help train armed forces in Cabo Delgado next month, state news agency Lusa reported on Tuesday. The World Health Organization was monitoring health risks in the wake of the attack, including cholera, malnutrition and respiratory infections, WHO Africa official Thierno Balde told Reuters. Balde said the true health impact of the attack may only become clear over the coming weeks.