The death toll from gang violence in Haiti this year rose to over 4,500 after 150 people were k!lled in the capital of Port-au-Prince over the past week, United Nations human rights chief Volker Turk said in a statement.

"The latest upsurge in violence in Haiti's capital is a harbinger of worse to come," Turk warned in the statement.

"The gang violence must be promptly halted. Haiti must not be allowed to descend further into chaos."

Violence has intensified dramatically in Port-au-Prince since November 11, as a coalition of gangs pushes for full control of the Haitian capital.

Well-armed gangs control some 80 percent of the city, routinely targeting civilians despite a Kenyan-led international force that has been deployed to help the outgunned police restore some government order.

"At least 150 people have been k!lled, 92 injured and about 20,000 forced to flee their homes over the past week," Turk's statement said.

In addition, "Port-au-Prince's estimated four million people are practically being held hostage as gangs now control all the main roads in and out of the capital".

Monica Juma, Kenya's presidential national security advisor, said on Wednesday that her nation backs calls from Haiti for the United Nations to consider turning the current international security mission into a formal UN peacekeeping mission.

Juma told a UN Security Council meeting on Wednesday that Kenya believed a formal peacekeeping mission could bring more resources to confront an escalating gang conflict.

The current mission has deployed just a fraction of troops pledged by a handful of countries and less than $100 million in its dedicated fund.

The Haitian capital has seen renewed fighting in the last week from Viv Ansanm, an alliance of gangs that in February helped oust former prime minister Ariel Henry.

Turk said that at least 55 percent of the deaths from simultaneous and apparently coordinated attacks in the capital resulted from exchanges of fire between gang members and police.

He also highlighted reports of a rise in mob lynchings.

Authorities said Tuesday that police and civilian self-defence groups had killed 28 gang members in Port-au-Prince after an overnight operation as the government seeks to regain some control.

The UN rights office said the latest violence brought "the verified casualty toll of the gang violence so far this year to a shocking 4,544 de@d and 2,060 injured".

The real toll, it stressed, "is likely higher still".

In addition, an estimated 700,000 people are now internally displaced across the country, half of them children, it said.

Turk warned that "the endless gang violence and widespread insecurity are deepening the dire humanitarian crisis in the country, including the impacts of severe food and water shortages and the spread of infectious diseases".

This was happening "at a time when the health system is already on the brink of collapse", he said, adding that "threats and attacks on humanitarian workers are also deeply worrying".

"Gang violence must not prevail over the institutions of the State," he said, demanding "concrete steps ... to protect the population and to restore effective rule of law".