LONDON, Feb 27 (Reuters) - S&P Global Platts will include U.S. WTI Midlands crude in its Brent oil benchmark from June, as previously guided, S&P's Vera Blei said in a benchmark update at the London Energy Forum on Monday.

Platts will accept 11 U.S. Gulf Coast terminals as supply points for WTI Midland crude into the Brent benchmark complex, she added.

Dated Brent, the underlying contract for Brent futures traded on the Intercontinental Exchange (ICE), is currently based on five North Sea crudes, the supply of which is in long-term decline. The five crude streams are Forties, Brent, Oseberg, Ekofisk, and Troll.

WTI Midland crude is produced in the United States and will be the first grade from outside the North Sea to be included in Brent.

Of the 11 U.S. Gulf Coast terminals, eight are located in Corpus Christi and three in Houston, with a combined storage capacity of 75 million barrels, a presentation slide showed.

The agency also confirmed it would increase the physical cargo size to 700,000 barrels from the current 600,000.

( Reporting by Shadia Nasralla and Alex Lawler; Editing by David Goodman)