By Ross Kerber

June 25 (Reuters) - Prominent U.S environmental organization Sierra Club Foundation said it will move $10.5 million away from BlackRock BLK.N because the top asset manager has not pressed portfolio companies enough on climate concerns.

The money in question is tiny fraction of BlackRock's $11.6 trillion in assets under management at the end of March, more than $1 trillion of which is held in sustainable funds and energy transition assets that the company continues to build up.

But the move underscores how BlackRock faces a balancing act on environmental and social issues with global customers who hold a wide range of views.

Sierra Club Foundation Executive Director Dan Chu said its change came after BlackRock cut its support for shareholder resolutions to a new low on issues such as emissions reductions, and left the Net Zero Asset Managers initiative in January.

"They never crossed the bridge where they would say they had an investment responsibility to fundamentally address the climate crisis," Chu said.

BlackRock has said many environmental shareholder resolutions are overly prescriptive and that its participation in industry climate efforts had "caused confusion" and legal issues.

“We support clients that have made net zero commitments for their organizations through our industry leading sustainable and transition investment platform, research, and analytics," a BlackRock spokesperson said via e-mail when asked about Sierra Club Foundation's decision.

Earlier this month Texas' comptroller removed BlackRock from a list of companies seen as boycotting the energy industry, a move that will make it easier for public agencies in the state to do business with the company.

BlackRock still faces opposing pressures including in Republican-controlled states where it remains restricted, and an upcoming review from New York City pension funds that want more robust emissions-reductions plans.

The Sierra Club Foundation oversees charitable activities of the Sierra Club and has some $200 million in all. It had warned BlackRock of its concerns in 2022.

The foundation said it will move its funds to Nia Impact Capital and to Xponance, which are both focused on sustainable investing.

(Reporting by Ross Kerber in Boston; Editing by Lincoln Feast.)

((ross.kerber@thomsonreuters.com; (617) 412 0093;))