Police arrested Nebojisa Medojevic, an MP from the opposition Democratic Front, and sent him to jail in the capital Podgorica on Friday to serve a two-month sentence.
He had been convicted of refusing to testify against the former long-term mayor of Podgorica, Miomir Mugosa, in a case involving corruption and misuse of office allegations.
The Montenegrin parliament's Committee on International Relations on Thursday failed to agree on the candidacy of the former Mayor of Podgorica, Miomir Mugosa, for the post of ambassador to Slovenia.
Opposition MPs and deputies from the junior ruling party, the Social Democratic Party, SDP, boycotted the session.
Montenegrin President Filip Vujanovic has set May 25 as the date for local elections, which will be held in accordance with the new EU-backed electoral law.
Elections will duly take place in Podgorica, Bar, Bijelo Polje, Danilovgrad, Zabljak, Kolasin, Plav, Pluzine, Pljevlja, Rozaje Savnik and Gusinje, Vujanovic said.