A Maltese court has charged three men with the murder of investigative journalist and blogger Daphne Caruana Galizia.
Caruana Galizia, 53, was killed October 16 when a bomb destroyed her auto as she was driving near her home.
The FBI, Europol, Finnish and Dutch security service personnel offered aid to the Maltese police.
The statement said the suspects had been arrested on the basis of "reasonable suspicion in connection with involvement in the murder" of Caruana Galizia.
Muscat announced the arrest of eight of the suspects in a statement and then added in a Twitter post that two more had been detained. Caruana Galizia wrote about some of those linked to the inquiry.
"Last month, her family had alleged that Farrugia had divulged confidential information that could hamper the investigation".
Galizia was reportedly following leads from the Panama Papers and had accused senior government functionaries and politicians of Malta of graft and money laundering.
All three have pleaded not guilty, according to reports.
Under Maltese law, they can be interrogated for 48 hours before a decision must be made to prosecute or release them.
Just before her death, Caruana Galizia, 53, had posted on her closely followed blog, Running Commentary, that there were "crooks everywhere" in Malta.
They took place in Marsa, where other vehicle bombings have occurred, as well as Zebbug, a village in central Malta, and in the northern town of St Paul's Bay.
They were charged with manufacturing the bomb, with killing the journalist, with taking part in organised crime, as well as possession of explosives.
Last week, a visiting delegation of European Parliament lawmakers left the island expressing concerns over the rule of law in the country and issued a warning that the "perception of impunity in Malta can not continue".
"Her reportage took aim even at the pinnacles of Maltese power: Earlier this year she reported that Michelle Muscat, wife of Malta's prime minister, secretly owned a mysterious company that had received more than $1 million from Azerbaijan".
Muscat said Monday of the slaying: "As I stated as soon as I learned about this barbaric act, we will leave no stone unturned to get this case solved".