WASHINGTON (REUTERS) - A US official on Tuesday signalled Washington's willingness to work with Rodrigo Duterte, the presumed victor in Monday's Philippine presidential election.

"We work with those elected," said the official, who spoke on condition of anonymity.

Duterte's victory has not been confirmed, but an unofficial count of votes by an election commission-accredited watchdog showed he had a huge lead over his two closest rivals, both of whom conceded defeat.

The US government typically does not comment substantively on foreign elections until the results are officially released.

On Monday, State Department spokeswoman Elizabeth Trudeau told reporters: "the United States congratulates the Philippines on holding inclusive and democratic elections. Our two nations have strong and enduring ties based on our shared respect for democratic values.

"We look forward to continuing those ties."

Duterte's vows to restore law and order have resonated with Philippine voters, but his incendiary rhetoric and advocacy of extrajudicial killings to stamp out crime and drugs have alarmed many who hear echoes of the country's authoritarian past.