Kenya's senate began impeachment hearings against Kenya's deputy president on Wednesday, hours after a court said the proceedings were constitutional, clearing the way for a vote on his dismissal this week.

Kenya's National Assembly voted on Tuesday last week to impeach the deputy president, Rigathi Gachagua, on 11 charges which included corruption, undermining the government and stirring ethnic hatred. Gachagua has denied all charges.

Gachagua has said the impeachment motion, backed by opposition lawmakers and allies of President William Ruto, was based on falsehoods that constituted a political lynching, according to court documents seen by Reuters.

As the senate opened proceedings on Wednesday, Gachagua denied the 11 charges read out by senate clerk Jeremiah Nyegenye.

"Not guilty," Gachagua said in response to each one.

Gachagua had launched a legal challenge against the impeachment proceedings in the high court, but Judge Erick Ogolla said the process could go ahead.

"At this stage, the process is a lawful, constitutional process, and the Senate will conduct a trial where all the issues being raised before the court will be raised and determined at the moment," the judge said in court.

"The application at this stage is premature and anticipatory," he said, referring to Gachagua's legal challenge.

The deputy president was Ruto's running mate in their 2022 election win, helping secure vital votes from the populous central Kenya region. But the men have since fallen out and political alliances have shifted.

Ruto fired most of his cabinet and appointed members of the opposition to what he called a unity government after nationwide protests against tax increases in which more than 50 people were killed.

During Wednesday's session, members of parliament seeking Gachagua's removal are expected to present their case to the senators.

Gachagua is expected to defend himself on Thursday before the vote. A two-thirds majority would be needed to dismiss him.

The court also said it would decide on October 29 whether Ruto can nominate a new deputy if Gachagua is dismissed.