Police also arrested nine men in connection with an arms seizure, saying they had clear evidence the suspects and their extended network were aiming to cause unrest in Thailand.
Thai police said on Sunday they had uncovered a plot to assassinate the country's prime minister, Prayuth Chan-ocha, after seizing a weapons cache belonging to a fugitive anti-junta activist.
It is the latest discovery of an alleged weapons stockpile belonging to a member of the Red Shirt movement, a political group loyal to exiled Prime Minister Thaksin Shinawatra, who was overthrown in a 2006 military coup.
Police on Saturday found dozens of rifles and grenades, and thousands of rounds of ammunition, at a house belonging to red shirt leader Wuthipong Kochathamakun, who has been on the run since 2014, when the military overthrew the government of Yingluck Shinawatra, the younger sister of Thaksin.
Police also arrested nine men in connection with the arms seizure, saying they had clear evidence the suspects and their extended network were aiming to cause unrest.
"We found a rifle with a scope. We guarantee that this is not to shoot at birds but was going to be used to assassinate the leader of the country [Prayuth Chan-ocha]," National Police Chief Jakthip Chaijinda said.
Prayuth was the army chief when the military ousted Yingluck Shinawatra from power.
The junta said the stockpiles showed there were groups loyal to the Shinawatra clan trying to create instability and justified their seizure of power.
Police chief Jakthip presented no other evidence of an assassination plot, but said Wuthipong and his network had always opposed the junta and the group had predicted on social media that the prime minister would be killed.