The secretary of Belarus' Security Council said in an interview on Friday that it was "unlikely" that a Ukrainian air defence missile downed on Thursday had entered Belarusian airspace by accident.
"Kyiv is striving to provoke a regional conflict by any means," Alexander Volfovich told the Russian state-owned outlet Sputnik Belarus. "An example of this is the recent incident with the destruction of the Ukrainian S-300 missile.
"There is little reason to believe that it entered our airspace by accident. By all appearances, it seems some plan was being realised here."
Belarus' defence ministry said on Thursday its air defence forces had shot down a Ukrainian S-300 surface-to-air missile near the village of Harbacha in the Brest region, some 15 km (9 miles) from the Belarus-Ukraine border.
The incident happened while Russia was firing dozens of missiles at cities across Ukraine in one of the biggest waves of strikes of the conflict.
In its daily briefing on Friday, Ukraine's General Staff said Russia had launched a total of 85 missile strikes, 35 air strikes, and 63 strikes from multiple rocket launch systems in the space of hours.
A regional military official in Belarus had played down the cross-border incident shortly after it occurred, saying: "Unfortunately, these things happen."
He compared it to an incident in November, when an S-300 believed to have strayed after being fired by Ukrainian air defences landed on the territory of NATO-member Poland, triggering fears of an escalation that were rapidly defused.
Nevertheless, the Ukrainian ambassador was summoned to the foreign ministry in Minsk on Thursday to receive a formal protest about the "extremely serious" incident.
Ukraine's defence ministry said it would investigate the incident, suggesting it was a Russian provocation and reserving the right to protect its own skies.
Belarus, which relies heavily on Russia for financial and military support, allowed Moscow to use its territory in February to start the invasion of Ukraine from the north.
Though Minsk has repeatedly said it does not intend to participate directly in the conflict, a flurry of military activity in Belarus, including the formation of a joint Russian-Belarusian unit, has aroused fears in Kyiv and the West that Russia may launch a fresh offensive from Belarusian territory.
(Reporting by Reuters; Editing by Kevin Liffey)