SAN’A, Yemen (AP) — The UN humanitarian chief called on the Yemeni government and Shiite rebels in the country’s north to agree to a temporary cease-fire Sunday to allow aid to reach the tens of thousands of people who have been displaced by intense fighting.

John Holmes, who was wrapping up a three-day visit to Yemen, said the government has responded positively to the cease-fire demand, but expected “words and promises to be turned into deeds.’’ He also urged both sides to respect international laws that are meant to prevent civilian casualties in conflict zones.

“There have been many allegations about the fighting, including allegations of very serious incidents,’’ said Holmes, referring to rebel claims that government warplanes have attacked and killed civilians.

“The government will investigate the most serious of these incidents,’’ Holmes, the UN’s humanitarian affairs and emergency relief coordinator, told reporters at a press conference in the capital San’a.

The five-year conflict in Yemen’s northern Saada province, which flared in August, has killed unknown numbers on both sides and displaced 150,000 people; many of them already impoverished and forced from their homes two or three times, according to the UN.

Shiite rebels took up arms against the government in 2004, complaining of neglect and the widening influence of hard-line Sunni fundamentalists, some of whom consider Shiites heretics.