Airstrikes by a Saudi-led coalition have killed 42 civilians in Yemen over the past week, with multiple children among the dead, the United Nations human rights office said Friday.

"In the week from August 17 to August 24, 58 civilians have been killed, including 42 by the Saudi-led coalition," spokeswoman Liz Throssell told reporters in Geneva.

The UN toll counted a series of strikes on Wednesday, including an attack on a hotel in Sanaa Governorate that killed 33 people and a separate strike on a house, also in Sanaa, that left six people dead. 

On Tuesday, "a woman and two children were killed and two women and two children were injured when an airstrike by the Saudi-led Coalition hit a house in Talan village" in Sanaa Governorate, according to a rights office statement.  

"In all these cases, in which civilians were killed and injured, witnesses said that there had been no warnings that an attack was imminent," it added.

The Saudi-led coalition entered Yemen's war in 2015 in support of the government against the Iran-backed rebels, who are in a fragile alliance with troops loyal to former president Ali Abdullah Saleh.