North Korea's coronavirus curbs have aggravated the country's human rights violations, a United Nations report said on Thursday, citing extra restrictions on access to information, tighter border security and heightened digital surveillance.

The report, released by the U.N. human rights office in Seoul and to be presented to the General Assembly in October, comes as rights groups say various authoritarian governments the world over have exploited the COVID crisis to tighten their grips and persecute opponents.

Based on interviews with defectors, information from other U.N. agencies and open source materials, the report says North Korea's border closure in early 2020 added to curbs on access to outside information. Authorities reinforced the military's presence, fences and closed-circuit television cameras and motion detectors along the border, the report said.

The country also employed new technologies, such as digital watermarking and the modification of hardware, to conduct surveillance and suppress access to foreign media content, while jamming radio frequencies from outside North Korea.

Those measures made it "more difficult for information to enter the country, such as through the distribution of USB memory sticks and micro SD cards," the report said.

Reuters could not independently verify the report's contents.

Pyongyang has repeatedly rejected accusations of rights abuses and criticised U.N. investigations on its situation as a U.S.-backed scheme to interfere with its internal affairs.

The isolated country declared victory over COVID and eased some restrictions, including a face mask mandate except in border regions, this month after reporting its first-ever outbreak in May.

North Korea has never confirmed how many people caught the virus in total, but instead reported daily tallies of fever cases until late last month.

The report also said the outbreak could have worsened North Koreans' access to adequate food and healthcare, citing a lack of medical infrastructure.