About 4,000 buildings are earmarked for demolition in an operation to clear illegal structures from river banks in Nairobi.

The operation expected to take two months kicked off yesterday in Kileleshwa.

A Java coffee house within the Shell petrol station and perimeter walls of several residential apartments in the upmarket estate were pulled down.

Some of the apartments were discharging effluent into the river.

Several kiosks, billboards and a swimming pool were also cleared.

Nairobi Central Business District chief Julius Wanjau, who is in charge of the operation, said the owners of the buildings had been issued with three months and extra seven days notices to vacate.

The notices have expired.

"We are going to continue with demolitions until we reach the National Museum. Then we will move to Gikomba, Ruai and Nairobi West," Wanjau said.

In June, the parliamentary committee on environment and natural resources was alarmed by the extent of encroachment when it toured waterways.

It identified Limuru Road, Lang’ata Road, Arboretum Road, Spring Valley, Globe Cinema Round-About, Riverside Drive, Westlands, Parklands, Fuata Nyayo estate in South B, Village market, Gem Suites in Riverside and Alina Villas in Spring Valley as among the areas with developments sitting on river banks.