Police in Nairobi are on alert Saturday - and tensions are high in Kenya's capital city - following three bloody days of protests.

At least 23 people have died since opposition leader Raila Odinga started nationwide demonstrations Wednesday. He and his supporters say the re-election last month of President Mwai Kibaki was fraudulent.

On Friday, the opposition said it would end the protests in favor of economic boycotts.

African leaders have been shuttling between the feuding factions to try to resolve the growing crisis.

About 650 people have died since the disputed election on December 27.

Former U.N. Secretary-General Kofi Annan is scheduled to arrive in Nairobi Tuesday to attempt to defuse the crisis.

In other news from Kenya, the U.N.'s refugee agency says it has suspended plans to deliver relief supplies to thousands of displaced Kenyans because of the protests and violence in the capital.

The agency flew tons of humanitarian supplies from Dubai to Nairobi Friday but says it is not able to deliver the aid because of the unrest.

An estimated 200,000 Kenyans have been displaced because of the violence. The U.N. Children's Fund estimates about half of those are children.

U.N. officials say the agency will resume the aid operation as soon as possible but it is not clear when that will be.

The relief supplies include stockpiles of plastic sheeting for shelter, mosquito nets and generators.

Some information for this report was provided by AFP and Reuters.