Finnish Prime Minister Antti Rinne speaks at a press conference after giving his resignation to President Sauli Niinisto at the President’s official residence M’ntyniemi in Helsinki, Finland, Tuesday, Dec. 3, 2019. Photo: Mikko Stigi/Lehtikuva via AP.

HELSINKI — Finland’s prime minister resigned Tuesday after a key coalition partner withdrew its support from his five-party government following a strike at the country’s postal service that spread to the national flag carrier Finnair.

Antti Rinne, who only took office in June, has faced heavy criticism in recent days over how he and a fellow Social Democratic minister dealt with a two-week strike of the country’s state-owned postal service Posti in November.

Rinne, who used to be a trade union leader, and Sirpa Paatero were accused of giving inaccurate and contradictory information in the run-up to the strike, specifically over the transfer of work contracts for 700 Posti package handlers, which effectively would have led to lower pay. Paatero, a minister who was in charge of state-owned companies, resigned on Friday.

Rinne had been under pressure for days over the Posti case and his role in the strike that ended on Nov. 27 after a compromise deal was reached that allowed package handlers to remain under current work contracts for now.

He said it became “obvious” after Paatero’s resignation that the Posti affair, which he described as “a messy case with plenty issues to be cleared” wouldn’t be settled with the minister’s departure.