Kenya's human rights commission has accused the police of operating alongside "armed criminal gangs" during the latest rallies

At least 11 people have been killed and dozens of others, including law enforcement officers, injured in a new wave of nationwide anti-government protests in Kenya, according to police officials in the East African country.

The latest casualties add to a growing toll from deadly unrest that has gripped Kenya in recent weeks.

The protests on Monday were held to mark the 35th anniversary of Saba Saba - Swahili for "Seven Seven" - a historic July 7, 1990 uprising against single-party rule that is now remembered annually as a symbol of resistance to repression and economic injustice.

In a statement late on Monday, the Kenyan National Police Service (NPS) said 63 people, including 52 police officers and 11 civilians, were wounded during the demonstrations, which it claimed were infiltrated by "criminals."

At least 19 vehicles - 12 belonging to the police, three to government agencies, and four to civilians - were damaged, according to the statement. A total of 567 people were arrested, the NPS said, praising its personnel for "demonstrating exceptional restraint and professionalism in the face of sustained violence and provocation by criminals."

Local daily The Nation reported that one protester was shot dead in Ol Kalou, Nyandarua county, while another survived after sustaining gunshot wounds.

Earlier, the state-run Kenya National Commission on Human Rights (KNCHR) reported at least ten people killed, 29 injured, two cases of abduction, and 37 arrests across 17 provinces.

READ MORE: Deaths reported during protests in Kenya (VIDEO)

The organization accused police of violating a court order requiring officers at protests to be in uniform, saying it observed "hooded officers, not in uniform" operating alongside "criminal gangs wielding crude weapons" in counties including the capital, Nairobi.

"The KNCHR calls on the government to immediately cease the harassment of Civil Society Organizations, Human Rights Defenders and the criminalization of legitimate human rights work," it said in a statement.

Late last month, 19 people were killed nationwide during demonstrations marking the first anniversary of last year's youth-led protests against a controversial finance bill - later withdrawn by the government - and the custodial death of Albert Ojwang, a blogger and teacher, according to the KNCHR. Six people, including three policemen, were charged with murder in connection to Ojwang's death, although they all pleaded not guilty.