Belarus on Tuesday said the new prospective western sanctions over its diversion of a passenger plane "border on the declaration of an economic war", and threatened to retaliate.
The US, EU, Britain and Canada joined forces on Monday to impose sanctions on several Belarusian top officials.
EU foreign ministers also prepared harsh economic sanctions on key Belarusian exports including potash, which is a common fertiliser ingredient, and petroleum products.
The Belarusian Foreign Ministry denounced the EU plans to introduce the sanctions, saying that they would hurt ordinary people.
It said the country would be forced to retaliate in ways that would hurt western companies.
On May 23, Belarusian flight controllers ordered a Ryanair jet travelling from Greece to Lithuania to land in Minsk, where authorities arrested Roman Protasevich, a dissident journalist who was on board.
Outraged leaders responded by barring the Belarusian flag carrier from EU airspace and airports, and directing European carriers to avoid Belarusian airspace. They warned of more sanctions to come.
Mr Protasevich, 26, co-founded a popular channel on a messaging app, which helped to organise mass protests.
Since his arrest, he has been shown repenting for his actions and praising Belarus’s authoritarian President Alexander Lukashenko on state TV.
The opposition and the West have slammed the broadcasts, saying he was coerced into making the confession.
Belarus has been shaken by months of protests fuelled by Mr Lukashenko’s re-election to a sixth term in an August 2020 election that was widely considered to be rigged.
The authorities responded to the demonstrations with a crackdown in which more than 35,000 people were arrested and thousands beaten by police.
Most opposition leaders have been jailed or forced to leave the country.
On Tuesday, Belarusian prosecutors said they would seek a 15-year prison sentence for Viktor Babariko, the former head of a Russia-owned bank who aspired to challenge Mr Lukashenko but was arrested in May 2020.
Mr Babariko, who has been in jail pending his trial, rejects the corruption charges against him as politically driven.