(Reuters) - A group of 17 Republican state attorneys general alleged that top U.S. asset managers, including BlackRock and State Street, were making improper or inadequate disclosures about their investments in China.

In a letter dated Thursday, the coalition said the companies were downplaying the risks associated with China, such as its status as a "designated foreign adversary" of the U.S. or its "apparent intention to invade Taiwan".

The letter was particularly scathing toward BlackRock, the biggest issuer of exchange-traded funds tracking emerging markets equities, according to VettaFi's ETF Database.

The rebuke comes as a bitter trade war unfolds between the two biggest economies of the world, and will put asset managers to the test as they navigate an increasingly complex geopolitical landscape.

U.S. authorities have previously scrutinized investment firms with exposure to China, citing concerns over potential human rights abuses and to curb the flow of American capital into a country they accuse of harboring ambitions to invade Taiwan.

Beijing denies allegations of human rights abuses and regards Taiwan as its own territory. Taiwan's government rejects those claims.

"Many BlackRock fund disclosures do not reflect China's apparent intention to invade Taiwan," the attorneys general wrote in the letter, adding that other "asset managers fail to address this issue as well".

Besides BlackRock and State Street, the group also took aim at Invesco, JPMorgan, Goldman Sachs and Morgan Stanley.

JPMorgan and Goldman Sachs declined comment, while the others companies did not immediately respond to requests for comment. Contents of the letter were earlier reported by Bloomberg News and the Financial Times.