June 8 (Reuters) - Funds that market themselves as being opposed to environmental, social or governance (ESG) investment considerations have seen a fall-off in new investor deposits, research firm Morningstar said on Thursday.

So-called "anti-ESG" funds have drawn attention as U.S. Republican politicians, often from energy-producing states, attack the growing attention paid to ESG factors by companies and investors.

One of the best-known funds, the Strive U.S. Energy ETF took in more than $300 million in the month after it launched last August. Strive co-founder Vivek Ramaswamy stepped down as executive chairman in February to run for U.S. president.

But flows into Strive and other such firms have since slowed significantly, Morningstar said in a new research paper.

After peaking at $376 million during the third quarter of 2022, more than five times the previous quarterly record, total net new deposits then fell to $188 million in the last three months of 2022 and to $69 million in the first three months of 2023.

"What started as a downpour slowed to a drizzle," the report states. One of its authors, Alyssa Stankiewicz, said in a telephone interview that most asset managers still see ESG risks, such as climate change, worth considering.

"Investing against ESG principles can seem too restrictive for some people," she said.

Stankiewicz cautioned other factors could be depressing flows however, including the funds' fees and mixed equity performance during the quarters studied.

Inflows to Strive accounted for the majority of net new deposits to anti-ESG funds in each of the three most recent quarters. A Strive representative did not immediately comment.

Total assets among the 26 anti-ESG funds Morningstar tracked stood around $2 billion as of March 31. A year earlier the figure was $282 million, but that excluded funds that had not yet launched, or adopted anti-ESG policies.

The funds practice anti-ESG efforts in various ways such as through proxy voting policies, or by favoring certain types of companies.

A fund that focused on sectors out of favor with ESG investors, like fossil fuels and tobacco, the Constrained Capital ESG Orphans ETF said this month it will be liquidated "due to inability to attract sufficient investment assets."

(Reporting by Ross Kerber; Editing by Sharon Singleton)