A poster carrying an anti-government message on the ground after a silent candlelight vigil to protest against the assassination of investigative journalist Caruana Galizia in Malta. Thomson Reuters WASHINGTON (Reuters) - The United States on Tuesday condemned the slaying of Maltese journalist Daphne Caruana Galizia and said the FBI had responded to Malta's request for assistance in investigating the car bomb attack that killed her.

State Department spokeswoman Heather Nauert said the United States condemned the "appalling violence that took place against her in the strongest terms," calling it a "cowardly attack" against a reporter who was dedicated to fighting corruption.

"We responded quickly to the prime minister's request for assistance. The government of Malta and Malta police force have been in contact with the FBI about the investigation and the FBI is providing specific assistance," said Nauert, who called for a "thorough, transparent and independent" probe.

Malta's home minister said on Tuesday that his EU country has also appealed to European forensic experts to help investigate the killing of the country's leading investigative journalist. Some EU lawmakers are pressing for closer scrutiny of Malta, which is considered a banking haven.

(Reporting by David Alexander; editing by Mohammad Zargham)