Army chief Gen Apirat Kongsompong on Monday said he strongly opposed a plan of the Pheu Thai Party to cut the defence budget -- and instead use the money to promote young entrepreneurs.

The army chief did not make a long statement. He instead referred to a song to show his opposition to the policy.

"They should listen to this tune -- Nak Phandin," he said.

Nak Phandin, translated literally as "worthless", is a song composed in 1975 to promote patriotic feeling during a fight against the now-defunct Communist Party of Thailand. It has previously been used to stir nationalism by the armed forces -- including by the National Council for Peace and Order after it seized power in 2014.

Khunying Sudarat Keyuraphan, a Pheu Thai candidate for the prime ministership, on Sunday said the party would slash the defence budget by 20%, and use the money as seed capital for startups by the young generation of business operators. The money would help up to 30,000 young entrepreneurs build up their businesses, she claimed.

Another key Pheu Thai member, Watana Muangsook, tweeted on Monday that more needed to be done to keep the Defence Ministry in check.

"We must make the armed forces leaner by reducing the excessive number of generals," he wrote. "The armed forces should be separated from politics."

Pheu Thai is not the only party ready to take on the influential armed forces. The Future Forward Party promises to end conscription if it wins power.