Estonia has concluded that an August arson attack on a defence company supplying Ukraine was commissioned by Russian security services, sharply escalating its accusation against Moscow. Prime Minister Kristen Michal said on Tuesday that the conclusion was based on intelligence gathered by Estonia's Internal Security Service, KAPO.

The fire broke out overnight on August 15 at a building in Tallinn used by Milrem Robotics, a maker of THeMIS unmanned ground vehicles supplied to Ukraine. Two Latvian suspects were detained in neighbouring Latvia on August 17, and a third the next day, before being handed over to Estonia.

Estonia did not disclose its evidence, citing the confidentiality of security services, but said the attack's method matched other sabotage carried out in Europe on Russia's behalf. Foreign Minister Margus Tsahkna called the act "absolutely unacceptable" and said Russia's charge d'affaires in Tallinn would be summoned.

The Kremlin dismissed the accusation. Spokesman Dmitry Peskov said the claims were "unfounded" and that Moscow "cannot take such statements seriously." Swedish Prime Minister Ulf Kristersson called the case "extremely serious" and said Sweden fully backs Estonia.