Prime Minister Prayut Chan-o-cha is not permitted by law to help the Palang Pracharath Party (PPRP) to canvass for votes, said Deputy Prime Minister Wissanu Krea-ngam.
Mr Wissanu said the matter was decided at a meeting between the Election Commission (EC) and various other agencies, after Gen Prayut accepted the PPRP's invitation to be its prime ministerial candidate last Friday.
He said the meeting passed a resolution that specifies what the prime minister should do in the lead-up to the March 24 election, and that the premier has been notified of the details.
Mr Wissanu said the resolution complies with election law, which prohibits a non-member of a party and candidates who are political post-holders from taking part in election campaigns.
Gen Prayut has previously turned down calls to run a caretaker government in the lead-up to the poll.
Separately on Wednesday, PPRP's deputy spokesman said the party will hold its first major rally since Gen Prayut accepted the party's nomination. The rally will take place in Kanchanaburi on Friday.
Meanwhile, Democrat Party leader Abhisit Vejjajiva advised Gen Prayut to join the public debate on party policies. "As a prime ministerial candidate, Gen Prayut should exchange his views and showcase his visions so people can make informed choices," he said.
