Estonia has asked the Finnish government to ease entry restrictions on workers arriving from Tallinn. Estonian Foreign Minister Urmas Reinsalu made the request in a Facebook post and in an interview with public broadcaster ERR.
The Finnish government announced new border traffic restrictions on Friday.
As of Wednesday, work-based entry from other EU countries, including neighbouring Sweden and Estonia, will be restricted to essential duties, defined as "work that is important for the functioning of society or for security of supply" or certain special groups such those involved in culture, sports and business.
Testing and quarantine recommendations will also be strengthened.
The new internal border controls will be in effect until at least 25 February. They are aimed at limiting the spread of new, more infectious Covid-19 variants in Finland.
Normally tens of thousands of foreign builders work in Finland, most of them Estonian.
Reinsalu said Finland's latest decision will in effect cut off work trips between the neighbouring countries.
"This is unacceptable to the Estonian government," he told ERR.
Tallink boss urges Estonian healthcare workers to strike
When the restrictions take effect, thousands of Estonians who go to work in Finland will have to decide whether to stay in Finland or return home to their families, according to the state broadcaster.
Also commenting on the Finnish government's decision was Paavo Nögene, CEO of the Tallink shipping line. In a tweet, he suggested that Estonian healthcare workers in Finland could go on strike in solidarity with the construction workers.
"Otherwise Finland's government won't realise that its choice is ugly. Those who are needed (will be allowed in), not others," Nögene wrote.