Thailand will hold a senate election in June, the government said Tuesday, the first poll for the upper house since a military coup a decade ago.

The cabinet of Prime Minister Srettha Thavisin approved plans for the complex, multi-round election -- which does not include a full public vote.

Ministers also agreed to hold a referendum asking Thais whether they would support changing the constitution, which was drawn up by the then-ruling junta in 2017.

The senate, whose 250 current members were appointed by the junta that seized power in 2014, played a crucial role in determining the outcome of last year's general election.

The progressive Move Forward Party (MFP) won most seats in the lower house, but its leader Pita Limjaroenrat was blocked from becoming prime minister because he did not muster enough support in the senate.

Srettha, whose Pheu Thai party finished second in the election, formed a coalition government with army-linked parties.

The upper house will be slimmed down to 200 senators, who will be chosen from 20 different fields of work and life including justice, education, public health, industry, arts and sport, the elderly and ethnic minorities.

Only those applying to become senators will be eligible to cast ballots, with three rounds of voting planned for June 9, 16 and 26.

Critics have said the process is both undemocratic and needlessly complicated.

"This isn't an election because the members of the senate do not come directly from the public," MFP spokesperson Parit Wacharasindhu told AFP.

The results of the election are expected on July 2.