Israel Thursday rejected calls from the United Nations and others for an international investigation into its deadly raid on a Gaza-bound aid flotilla. An official in the prime minister's office says there is “no case in recent history” where a democratic country's army involved in the deaths of civilians in an overseas operation has been subjected to an international investigation. Israel's military already is investigating the raid. Israel's Foreign Minister Avigdor Lieberman embraced a US suggestion in an effort to calm a global furore. “I am in favor of an investigation. We have enough high-level legal experts ... if they want to take on observers from the outside, they can invite observers,” Lieberman said on Israel Radio. “I propose we use South Korea as an example,” he said, referring to an investigation launched by Seoul that included experts from the United States, Australia, Britain and Sweden, after the sinking of one of its warships in March. US Vice President Joe Biden suggested an Israeli probe with international involvement. Meanwhile, hundreds of pro-Palestinian activists seized by Israeli commandos in the bloody raid returned to Turkey to a hero's welcome Thursday. Thousands of mourners flocked Thursday to a funeral for Turkish activists, as President Abdullah Gul told an outraged nation that ties with Israel would never be the same again. Coffins of most of those killed, draped in Turkish and Palestinian flags, were brought to Istanbul's Fatih Mosque for the service before the bodies were taken to their home towns for burial. “Turkey will never forget such an attack on its ships and its people in international waters. Turkey's ties with Israel will never be the same again,” Gul told a news conference. “Israel made one of the greatest mistakes in its history. It will see in time what a huge mistake it made,” he said. One large banner read “Murderous Israelis: Take your hands off our ships” while others in the crowd held signs with slogans like “From now on, nothing will be the same” and “Intifada is everywhere – at land and at sea” – in reference to the Palestinian uprising against Israeli occupation. Turkey's ambassador to Israel, Oguz Celikkol, who was recalled after Monday's raid, also returned to Turkey Thursday, Anatolia news agency said. Bulent Yildirim, head of the Islamic charity which spearheaded the campaign to break the Gaza blockade, charged that Israeli soldiers had killed activists indiscriminately when they stormed the Mavi Marmara. Forensic experts in Istanbul found bullet marks on the bodies of all the victims and determined that one was shot at close range. Two Swedes aboard the Gaza-bound aid flotilla intercepted by Israeli forces this week said in a radio broadcast Thursday they had witnessed “premeditated murder” aboard the Turkish ship that came under the heaviest attack. “We were witnesses to premeditated murders,” said historian Mattias Gardell who was on the Mavi Marmara along with his wife, fellow historian Edda Manga, when Israeli commandos attacked the ship early Monday, killing at least nine people. “This was a military attack on a humanitarian aid operation far out in international waters ... It was a very surprising and aggressive overreaction by Israel,” he told Swedish public radio upon arrival in Istanbul with planeloads of nearly 500 activists, including seven Swedes, early Thursday. Meanwhile, an Irish aid boat is steaming toward Gaza where it hopes to deliver vital supplies at the weekend, but those on board will not resist arrest by Israeli forces, organizers said Thursday. The MV Rachel Corrie -- carrying 15 people including a Nobel Prize winner and a former top UN official -- is some 720 km from where six boats were boarded in the botched Israeli raid.