Police blocked major roads leading to Nairobi and heavily restricted vehicle traffic on Monday, Reuters witnesses and Kenyan media said, as the country braced for protests to mark the anniversary of pro-democracy rallies.

Activists rally each year on July 7 to mark the date in 1990 when opponents of then-president Daniel Arap Moi launched a bid to transform the country into a multiparty democracy. The protest is called "Saba Saba" - "seven seven" in Kiswahili - because of the date. 

This year's rally comes after largely youth-led protests in June last year that initially focused on tax hikes but expanded to cover issues such as corruption, police brutality and unexplained disappearances of government critics.

The government is committed to protecting life and property during protests, Interior Minister Kipchumba Murkomen said on his X account on Sunday.

"Our security agencies are on high alert to deal decisively with criminals and other elements of ill intent who may seek to infiltrate peaceful processions to cause havoc, mayhem, or destruction of property," he said.

On Sunday, unidentified people forced their way into the offices of the non-profit Kenya Human Rights Commission to stop a press conference ahead of Monday's protests.

At least one person, a board member, was injured, Ernest Cornel, who works at the commission, said.

Police spokesperson Muchiri Nyaga did not immediately respond to a Reuters' request for comment.

Most schools and at least one shopping mall remained closed on Monday, Reuters witnesses said.

The death of Albert Ojwang, a teacher and blogger, in police custody in June gave fresh impetus to protests, with the government-funded Kenya National Commission on Human Rights reporting 19 deaths across the country during demonstrations last month.

Prosecutors approved murder charges against six people, including three police officers, over Ojwang's death. All six pleaded not guilty.