UNITED NATIONS, March 15 (Reuters) - China blocked the United States on Wednesday from broadcasting on the internet an informal United Nations Security Council meeting on human rights abuses in North Korea, diplomats said.

The meeting will be held on Friday, but the 15 council members have to unanimously agree to allow it to be webcast. Diplomats said it is rare for a broadcast to be blocked.

The Security Council has regularly discussed human rights in North Korea since 2014 in public formal meetings and behind closed doors. China and Russia have long said they do not believe the council - charged with maintaining international peace and security - should be discussing human rights in North Korea.

China told its council colleagues on Wednesday in an email, seen by Reuters, that the discussion - "won't bring any benefit, and we have been against the holding of this ... meeting from the very beginning."

"Therefore, we have to object to the webcasting of this meeting by UN WebTV," China said.

Pyongyang rejects accusations of human rights abuses and blames sanctions for a dire humanitarian situation in North Korea. The country has been under U.N. sanctions over its ballistic missile and nuclear programs since 2006.

"Why is China so afraid of discussing human rights publicly?" said a U.N. diplomat, speaking on condition of anonymity.

The aim of the informal council discussion is to spotlight rights abuses in North Korea and "identify opportunities for the international community to promote accountability," according to a note to council members last week from the United States and elected council member Albania, which is co-hosting the meeting.

The discussion comes amid heightened international tensions with North Korea.

Pyongyang has launched dozens of ballistic missiles in the past year, including intercontinental ballistic missiles.

But China and Russia oppose any further action by the Security Council, arguing that putting more pressure on North Korea would not be constructive. The pair vetoed a U.S.-led push to impose more U.N. sanctions on North Korea in May last year.