Filipino president Rodrigo Duterte has instructed his country's army and police force to shoot him if he ever becomes dictator and stays on beyond his term.

He made the comments after his critics accused him of ordering loyalist politicians in the country's Congress to change the constitution and introduce a federal system which would allow him to stay in power after 2022, when his single term ends.

Seeking to dispel speculation about the changes, the 72-year-old told soldiers during an army base visit: “If I overstay and wanted to become a dictator, shoot me, I am not joking."

Security forces should not allow anybody to mess with the constitution, he said, adding: “It is your job to protect the constitution and to protect the people. Remember, it is your solemn duty.”

Mr Duterte has advocated federalism to tackle inequality, empower provinces and recognise the country’s diverse makeup.

But controversial leader, who promised to kill every drug dealer and user and feed their corpses to the fish in Manila Bay, during his presidential election, has denied that he has ordered allies to introduce a federal system.

However, last week his political supporters voted to form a constituent assembly that could revise the charter by May, scrapping mid-term elections next year and extending the terms of all elected officials.

Constitutional reform remains a divisive issue in the country.

The most controversial quotes from Rodrigo Duterte Show all 9 1 /9 The most controversial quotes from Rodrigo Duterte The most controversial quotes from Rodrigo Duterte On killing drug addicts “These sons of whores are destroying our children. I warn you, don’t go into that, even if you’re a policeman, because I will really kill you. If you know of any addicts, go ahead and kill them yourself as getting their parents to do it would be too painful” The most controversial quotes from Rodrigo Duterte Message to China “I will go there on my own with a Jet Ski, bringing along with me a [Phillipino] flag and a pole, and once I disembark, I will plant the flag on the runway and tell the Chinese authorities, ‘Kill me’ ” AP The most controversial quotes from Rodrigo Duterte Christmas message to law-breakers “If you do not want to stop, and just continue committing crimes, then this would be your last Merry Christmas” AP The most controversial quotes from Rodrigo Duterte On sex life “I was separated from my wife. I’m not impotent. What am I supposed to do? Let this hang forever? When I take Viagra, it stands up” AFP/Getty Images The most controversial quotes from Rodrigo Duterte On the drugs trade “None of my children are into illegal drugs. But my order is, even if it is a member of my family, ‘kill him'" AP The most controversial quotes from Rodrigo Duterte Insulting the Pope “We were affected by the traffic. It took us five hours. I asked why, they said it was closed. I asked who is coming. They answered, the pope. I wanted to call him: ‘Pope, son of a wh**e, go home. Do not visit us again’” AFP/Getty Images The most controversial quotes from Rodrigo Duterte Joke about rape “I saw her face and I thought, 'What a pity... they raped her, they all lined up. I was mad she was raped but she was so beautiful. I thought, the mayor should have been first” AFP/Getty The most controversial quotes from Rodrigo Duterte Insulting Barack Obama "Mr Obama should be respectful and refrain from throwing questions at me about the killings, or son of a bitch, I will swear at you in that forum" REUTERS The most controversial quotes from Rodrigo Duterte On Abu Sayyaf Islamic militants "If I have to face them, you know I can eat humans. I will really open up your body. Just give me vinegar and salt, and I will eat you. If you annoy me to the fullest... I will eat you alive. Raw" EPA

Critics have accused politicians of trying to prolong their stay in office, or of seeking a way for the hugely popular Mr Duterte to remain in power beyond the end of his term.

Opponents warn it could lead to a repeat of the oppressive rule of late dictator Ferdinand Marcos, saying they are troubled by Mr Duterte’s admiration for Marcos and his similar authoritarian traits.

Mr Duterte’s spokesperson, Harry Roque, has repeatedly said the President has no desire to stay longer than his term and, if anything, would prefer to retire earlier.