Estonia's leader has been a staunch supporter of Ukraine as the country battles the Russian invasion.
Opposition figures in Estonia have called on Prime Minister Kaja Kallas to resign after it was revealed her husband's company was continuing to operate in Russia.
The Center Party announced on Friday it was starting to discuss a no-confidence motion against her, while another opposition group Isamaa said the scandal has caused "considerable damage to the interests and reputation of Estonia".
Estonian public broadcaster ERR reported on Wednesday the haulage firm Stark Logistics, part-owned by Kallas's husband, Arvo Hallik, continued doing business with Russia after it invaded Ukraine.
The revelations are an embarrassment for Kallas, who has repeatedly expressed her strong support for Kyiv.
All trade with Russia must "stop as long as the war of Russian aggression against Ukraine continues," she said following the revelations.
In a press release issued earlier this week, Stark Logistics said it had only one Estonian client, Metaprint, which is currently in the process of closing its plant in Russia.
Kallas said her husband's company was assisting his Estonian clients in Russia "in accordance with the laws and sanctions" currently imposed.
On Friday, Hallik apologised "for the harm caused to my wife", saying he would immediately sell his shares in Stark Logistics and retire from the company.
He maintained she "was not aware" of his professional activities.
Metaprint CEO and majority shareholder of Stark Logistics Martti Lemendik told ERR on Friday that the company has generated nearly €30 million in sales in Russia since Moscow invaded Ukraine.
Two polls commissioned in the wake of the scandal show that the bulk of those surveyed want Kallas to step down as PM. But supporters from her liberal Reform Party want her to stay put.
Some 57% of respondents said Kallas should reign as head of government, 31% answered she should provide an explanation but stay on, while 7% opted for "do nothing", according to a poll commissioned by the Conservative think-tank the Institute for Societal Studies
Some media outlets in Estonia have also called for Kallas to stand down.
The daily newspaper Eesti Päevaleht claimed she "should submit her letter of resignation", though without "necessarily leaving her post".
Deeming Kallas' explanations insufficient, the Postimees newspaper advised the PM "to start packing her bags today to avoid even greater embarrassment in the future."
Kallas' government, a coalition between his Reform Party, the Social Democrats and Estonia 200, was formed on 17 April. It has 60 seats out of 101 in the country's parliament.
Kallas will face two select committees next week.