The Kenyan capital, Nairobi, was rocked by violence Saturday when police fired tear gas and water cannons on angry crowds protesting the government's failure to implement constitutional changes. Frustration with the government has been building for some time.

The sounds of police helicopters, sirens and shouting reverberated through the streets of Nairobi Saturday, after hundreds of people gathered to protest the Kenyan government's failure to deliver a new constitution, which it promised to do by June 30.

The government had previously banned the rally, organized by former delegates of a national constitutional conference and some politicians.

But protesters vowed to meet anyway to express their anger with the government's foot-dragging and President Mwai Kibaki's political maneuvering.

Protester Collins Odhiambo Aluoch explains.

"The main thing is that President Kibaki promised Kenyans to be given a constitution after 100 days," he said. "It has taken 18 months. We have never seen any constitution. We need it, because that is why we voted for NARC [party in power]."

Police dispersed the crowd, which then took to the streets in running battles all day. At least seven people were reported injured.

For years, Kenyans have been eagerly awaiting a new constitution that would, among other things, limit the powers of the president.

The National Rainbow Coalition, or NARC, swept into power in December 2002, on the promise of giving the country a new constitution within 100 days.

A national constitutional conference produced a draft document last March, and President Kibaki said the final version would be released June 30. But political wrangling and court challenges prevented this from happening.

Analysts say President Kibaki's coalition government is slowly disintegrating, as opposition groups that gathered to form the coalition are now fighting among themselves for power and differences over the constitution.

Earlier this week, President Kibaki reshuffled the Cabinet in an attempt to quell the internal bickering, but only managed to inflame tensions.

The U.S. ambassador to Kenya, William Bellamy, criticized the Kenyan government Friday, saying that the political infighting is costing the government its credibility.

"To be honest, that critical transition is not going as well as many hoped it would," said Ambassador Bellamy. "Political events of the past two days only serve to confirm that sorrowful judgment."

Mr. Bellamy also criticized the government's failure to enforce the anti-corruption legislation.

In recent weeks, details have emerged about corrupt dealings involving close allies of President Kibaki.

Mr. Bellamy said the government needs to make a lot of changes, but, in his words, the question we now all ask is whether the political will still exists to do it.