BRUSSELS (Reuters) - European Union leaders called on Malta on Thursday to carry out a full investigation with international help over the killing of the country s best-known journalist, and the EU parliament agreed to hold a debate on media freedom on the island. Malta s Prime Minister Joseph Muscat has already called in foreign investigators to help look into the car bomb that killed Daphne Caruana Galizia, who wrote about widespread breaches of the rule of law and corruption on the island. Malta is the smallest EU country but is home to a disproportionately large financial services sector and is the continental hub for the flourishing online gaming industry.  Muscat, who himself had sued Caruana Galizia after she accused him and his wife of wrongdoing, promised a thorough investigation of the killing.  We will not exclude any sort of path, any sort of measure to make sure we get to the bottom of it,  Muscat told reporters arriving to the EU summit in Brussels. The president of the European Parliament Antonio Tajani said he raised the issue in a meeting with EU leaders.  I called for an international investigation to fully clarify an event of unprecedented gravity,  he said, adding that the leaders broadly shared the view. During the meeting, German Chancellor Angela Merkel backed an international investigation, EU officials said. Diplomats said that France, Spain and Portugal had also stressed the need for involvement of foreign investigators. Before the meeting Muscat said the U.S. Federal Bureau of Investigation (FBI) and Dutch investigators would help in the case and other security forces, including London s Scotland Yard, could join. The chief of the Maltese police later denied possible involvement of the British police. Political leaders of the EU Parliament agreed to hold a debate next Tuesday on  protection of journalists and the defense of media freedom in Malta , according to a draft agenda adopted on Thursday.   Malta is a Mecca for money launderers and tax avoiders,  Greens EU legislator Sven Giegold said.  Malta s center of power suffers from a culture of impunity unlike hardly any other country in the EU. Europe must no longer turn a blind eye to the way in which the rule of law is flouted in Malta.  Muscat has rejected criticism that he has allowed wealthy foreigners to hold great sway over Malta, and says the financial services sector is as transparent and compliant as any other European jurisdiction. 