Romania has charged six men with treason for plotting a coup with links to Russia, prosecutors in the NATO ally said, accusing them of conspiring "to undermine the sovereignty and independence of the Romanian state".

Romanian prosecutors said Thursday that they arrested and charged six people with treason, accusing them of colluding with Russia to "undermine" the country. The case has already led to the expulsion of two Russian diplomats — Russia's military attache and his deputy — who were declared persona non gratae on Wednesday.

Romanian prosecutors detained six people on charges of forming an organised criminal group and treason, they said on Thursday, adding that members of the group repeatedly contacted agents of a foreign power both in Romania and in Russia.

Romanian prosecutors detained six people suspected of allegedly plotting to overthrow the government and withdraw the Black Sea nation from NATO with Russia’s help.