Forces from an alliance of Arab states seized two entrances to the airport in Yemen's main port city on Friday, in an offensive against the Iran-aligned Houthi movement that the United Nations fears could trigger a famine imperilling millions of lives.

The swift advance was an important early success for the Saudi- and United Arab Emirates-led alliance, which launched the operation in Hodeida three days ago and says it can seize the city quickly enough to avoid interrupting aid to the millions facing starvation.

"We saw the resistance forces in the square at the northwestern entrance to the airport," said a Hodeida resident, referring to Yemeni allies of the Saudi-led coalition. Two Yemeni military officials allied to the coalition confirmed this.