Rain-swollen water levels at two Kenyan hydroelectric dams are at “historic highs” and people downstream should move away, the Cabinet warned on Tuesday, and ordered residents of flood-prone areas across the country to evacuate or they’ll be moved by force.

Kenya, along with other parts of East Africa, has been overwhelmed by flooding that killed over 70 people on Monday alone and in recent days has blocked a national highway, swamped the main airport and swept a bus off a bridge. More than 150,000 people are displaced and living in dozens of camps after more than 30,000 were swept away.

With seasonal rains forecast to increase in the coming weeks, the Cabinet said residents of areas with flooding or landslides in the past, and residents near dams and rivers considered at high risk, will have to evacuate by Wednesday. Those who don’t will be moved by force.

It was not clear how many people will have to move, or how notifications and evacuations would be carried out on short notice, especially in crowded informal neighbourhoods in major urban areas.

“We will assist you all and ensure we resettle you in an area that the government has identified,” said President William Ruto during a visit to the Mai Mahiu area, an hours’ drive west of Nairobi, where a river broke through a blocked tunnel early on Monday and killed at least 70 people.

As bodies were pulled from under fallen trees, there was frustration with authorities. “That tunnel started blocking on Wednesday and the local government knew about it,” said resident Sam Njoroge, who said relatives were killed. “So according to me, the government was negligent because if they acted fast they would have unblocked the tunnel and all these deaths would not have happened.”

On Kenya’s longest river, the Tana, to the east, water levels at the Masinga and Kiambere hydroelectric dams have reached historic highs, the Cabinet said.

On Sunday, flooding on the Tana capsized a boat and seven people died, with another 13 reported missing. Earlier this month, high waters on the Tana swept a bus from a bridge. All 51 passengers were rescued.

Flooding in East Africa also has killed more than 155 people, injured over 230 and affected more than 200,000 others in neighbouring Tanzania.

• An AP report