The individuals are suspected of providing information about military and strategic objects in response to requests from Russian intelligence agencies.
The suspects were detained in the framework of two separate investigations.
In the first probe, suspicions were brought against a civilian resident of Šiauliai, northern Lithuania, who earlier worked for the Air Force, and a Lithuanian citizen who has a permanent residence permit to live abroad.
In the second investigation, suspicions were brought against a Lithuanian civilian who "received money for information about military objects related with the Navy," Criminal Police chief Rolandas Kiškis told journalists.
The investigation was opened on a tip-off from military intelligence and involved a few dozen searches.
The suspects face up to 15 years in prison.
Colonel Remigijus Baltrėnas, the head of the Military Intelligence Service, told the news conference on Thursday that the suspects possessed non-classified information.
"Regardless of the fact that the spying operations involved provision of non-classified information and that the detained individuals did not need to have permits to handle classified information, this does not deny the danger of the spying and the threat to state security," said Baltrėnas.
In his words, they were also collecting information about other individuals who could be recruited.
"We warn all citizens of the Republic of Lithuania that the threat of recruitment always remains, especially during visits in countries that are not members of NATO, and that citizens of the Republic of Lithuania should be very careful and alert, furthermore, they should notify intelligence institutions of the Republic of Lithuania without delay after sensing signs of recruitment, talking into working for foreign countries. This should help prevent and reduce possible consequences for Lithuanian state security, as well as benefit the citizens of Lithuania," Baltrėnas told the news conference.
Prosecutors say a total of 12 persons have been identified in Lithuania since 2014 who faced spying suspicions. Five of the individuals have already been sentenced to jail terms.
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