LONDON — A humanitarian crisis is emerging in Egypt’s volatile northern Sinai province, Human Rights Watch said Monday.

An Egyptian military campaign launched in February against an active Islamic State affiliate is choking off food, medicines and other vital supplies to an estimated 420,000 residents of four northern cities in need of assistance, the group said in a report.

Security forces, in a quest to weaken the Islamic State branch, known as Wilayat Sinai, have imposed barriers on the movement of people and goods in northern Sinai, including blocking roads and other transport arteries. That has triggered shortages of food, medicines, cooking gas and other essentials.

There are large-scale electricity and water shortages in much of the eastern part of northern Sinai province, aggravating residents’ woes.

“A counterterrorism operation that imperils the flow of essential goods to hundreds of thousands of civilians is unlawful and unlikely to stem violence,” Sarah Leah Whitson, Human Rights Watch’s Middle East and North Africa director, said in a statement.

Whitson said the military’s actions “border on collective punishment” and reveal “the gap between what President Abdel Fatah al-Sissi claims to be doing on behalf of the citizenry and the shameful reality.”

It is difficult to independently verify conditions in northern Sinai. The government has banned foreign journalists from entering the area. Human Rights Watch said it interviewed two media workers residing in the region and 13 residents. The group said it also reviewed satellite images, video footage, official statements and social media posts to arrive at its conclusions.

If the restrictions on the movement of people and goods continues, the group warned, the crisis could worsen. Northern Sinai is already one of the poorest regions in Egypt, affected by years of military operations.

Col. Tamer al-Rifai, a military spokesman, rejected the report’s findings, denying that there is a food crisis. In an interview on Monday with Sada El-Balad, a pro-government television channel, he said the military has provided residents with free food and other “basic commodities” in the areas most affected by the military operations.

Human Rights Watch said the road closures were isolating cities from one another as well as isolating northern Sinai from Egypt’s mainland. And while the group acknowledged that the army has become the main source of food, it noted that the military was not meeting residents’ needs. Some markets in the eastern cities of Rafah and Sheikh Zuwayed, nestled along the border with the Gaza Strip, have almost run out of goods, Human Rights Watch said.

The current military campaign follows a directive by Sissi to restore stability and security to northern Sinai, the Western Desert and other tense areas by force. In November, gunmen attacked a Sufi mosque in northern Sinai, killing more than 300 worshipers. The attack was widely believed to have been orchestrated by the Islamic State, which has been waging a guerrilla insurgency in the region since 2013.

The military campaigns have forced the closure of schools and universities and shattered trade and other economic activities in the northern Sinai region.