The leader – who has in the past compared himself to Hitler and launched a ‘War on Drugs’ claiming thousands of lives – made the comments during a speech.
He claimed he had gone up to her room while she slept and touched her inappropriately.
He then compounded it by saying he later returned to the room to assault her a second time.
Duterte – who was telling an anecdote about a confession he had made to a priest as a schoolboy – faces calls to resign, with his actions said to bring shame on the entire nation.
But a spokesman for the strongman later claimed he had made it up.
Describing the incident, which happened when he was a teenager, Duterte said:
“I went to the room of the maid. I lifted the blanket.
“I tried to touch what was inside the panty. I was touching. She woke up. So I left the room.”
And speaking to a priest, who had asked him to confess a sin, he said he tried to perform a sex act when he returned to the maid’s room, a transcript reveals.
He made the remarks during a speech about land reform, but went off on an attack on the Catholic Church over its sexual abuse scandal.
In response human rights group Gabriela called on Duterte to step down.
The organisation said:
“This latest confession has brought shame not only himself but on the entire nation.
“He has proven himself unworthy of his position and should resign.”
But the president’s spokesman, Salvador Panelo, later claimed his boss had made the story up.
Duterte has long been criticised for his attitudes toward women.