People place candles at a memorial for investigative journalist Daphne Caruana Galizia, who was murdered in a auto bomb attack, during a vigil in Valletta, Malta November 16, 2017.
"In October, Caruana Galizia was killed by a auto bomb so big it hurled the vehicle almost 90 yards into a field".
Muscat said a joint team of police, military and security services made the arrests following a almost seven-week investigation carried out with help from the FBI, Europol and Finnish intelligence.
Eight Maltese citizens were arrested because of "reasonable suspicion" for their involvement in Caruana Galizia's killing, Muscat told reporters at a news conference.
Prime Minister Joseph Muscat said some of the 10 detainees were already known to the police while others had criminal records.
"It is of little comfort for the Prime Minister of this country to say that he will "not rest" until the perpetrators are found, when he heads a government that encouraged that same impunity", Matthew Caruana Galizia wrote in mid-October.
The journalist's family are taking legal action against the island's police, saying the investigation into the killing can not be impartial and independent since Caruana Galizia wrote critical articles about both the senior officer now running it, Silvio Valletta, and his wife, a top government minister.
"It is important to ask whether they are not also leaking information to other suspects, some of whom could be in or close to government", the statement continued. According to Maltese law, the police have 48 hours to question the suspects, charge them or release them.
Malta has a reputation as a tax haven in the European Union and has attracted companies and money from outside Europe as well.
Caruana Galizia, 53, was one of Malta's most prominent public figures, thanks to a widely read blog she used to expose crime and corruption on the small but economically booming nation.
They were charged with manufacturing the bomb, with killing the journalist, with taking part in organised crime, as well as possession of explosives. Due to her reports, she had been sued 36 times in the past nine months before her death.
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".