The Social Democrats had called for Ligi's resignation over the remarks, which he made on Facebook in reference to a ETV talk show on which both of the ministers had appeared the night before.

On the "Foorum" program, the two had clashed over why emigration was such a problem for Estonia, with Ligi blaming the Soviet occupation and falling behind in comparison to the West, while Ossinovski said that could not be considered an excuse.

Ligi said on social media that Ossinovski's opinion reflected "rootlessness" and "ignorance." He elaborated, saying it was ignorance about Estonia's lowly starting position in the 1990s that was leading many people to leave the country.

"He, an immigrant's son from a pink party, should be super-careful, but he doesn't even know how to look," wrote Ligi.

Ossinovski is the son of Oleg Ossinovski, a naturalized citizen who is one of the country's richest men. Ossinovski also has roots in Estonia through his mother. He is equally fluent in Russian and Estonian and his loyalty is almost universally considered above reproach.

He is also one of the Social Democrats' rising stars and seen as a key hedge against Center Party power, which is traditionally supported by Russian speakers. In last October's local elections, Ossinovski led a Social Democratic resurgence in the city of Narva.

A few hours later, Ligi apologized. He added: "I don't and cannot have any criticism for his origin; on the contrary, I admire his Estonian-mindedness and language ability."

But by that time the damage was done.

Ossinovski himself said he would step down if he were in Ligi's shoes, and told uudised.err.ee it didn't come as a surprise from Ligi.

Ligi has long been considered a near-indispensable cabinet member and the architect of many of former PM Andrus Ansip's internal devaluation and austere fiscal policies.

But he also has a penchant for controversial remarks and insulting rivals, often on the air.

The Social Democrats' chairman Sven Mikser referred to such incidents and said that it was high time that Siim Kallas, a former central bank governor and premier also from the Reform Party, replace Ligi.

From the opposition, Center Party MP Jüri Ratas also called for Ligi to step down. IRL's Urmas Reinsalu said it was "not thinkable" that Ligi continue.

PM Taavi Rõivas weighed in an attempt at conciliation, saying it "looked bad" and that Ligi was right to apologize.

"I hope Jevgeni accepts the apology and it will not lead to more serious conflicts between Cabinet members." he said.