The leader of a popular new Thai political party has met with police to hear criminal charges of sedition against him filed by the ruling military junta.

Thanathorn Juangroongruangkit, leader of the Future Forward Party that ran a strong third in elections last month, was greeted by a crowd of around 300-400 supporters chanting "Keep fighting, Thanathorn!"

The charges carry a maximum prison sentence of up to nine years. He has said the legal action against him is politically motivated and expected.

Thailand has been led by a military government since a coup in 2014.

The election results are due to be ratified by May 9. Parties are in a race over which side will be able to gather enough support to form the next government.