SEOUL, March 28 (Reuters) - Yang Jiechi, one of China's top diplomats, will brief officials in Seoul on Thursday, including President Moon Jae-in, on Chinese President Xi Jinping's meeting with North Korean leader Kim Jong Un, the presidential office in Seoul said on Wednesday.

Separately, a senior Blue House official said it was "positive" for the North's upcoming summit with South Korea and the United States that Kim Jong Un had mentioned denuclearisation during his meeting with Xi this week.

State media in North Korea and China said on Wednesday Kim Jong Un had visited Xi and pledged to denuclearise the Korean peninsula. Xi promised China would uphold its friendship with its isolated neighbour. (Reporting by Christine Kim Editing by Paul Tait)