UN Secretary-General Antonio Guterres condemned Monday's reported gang attack in Gros-Morne, Artibonite department, Haiti, his spokesman said on Wednesday.

The horrific attack, which reportedly left at least 11 people dead, is another reminder of the heavy toll that gang violence continues to take on Haitians living in areas under the control or influence of armed gangs, said Stephane Dujarric, the spokesman.

The incident also underscored the urgency of strengthening security efforts in Haiti, including through the full deployment of the Gang Suppression Force (GSF), and the need to improve the broader efforts to address the drivers of violence and instability in the country, the spokesman said at a regular briefing.

More than 3,000 people were killed in Haiti between January and June, he said, citing data from the UN Office of the High Commissioner for Human Rights.

"We and our partners continue to provide food, healthcare, psychosocial support and emergency cash assistance. However, humanitarian needs continue to outpace available resources," said the spokesman.

The humanitarian needs and response plan for Haiti, which requires $880 million to help 4.2 million people, is still less than half funded with just three months left in the year, said Dujarric.

The spokesman said on Tuesday that the secretary-general welcomed the adoption of Security Council Resolution 2829, which extended the GSF's mandate in Haiti for six months.

The secretary-general called on member states to build on this momentum by working without respite to ensure the timely deployment of the remaining personnel so the force can fully carry out its important mandate, Dujarric said.