* Futures down: Dow 0.67 pct, S&P 0.5 pct, Nasdaq 0.83 pct
By Sruthi Shankar
June 25 (Reuters) - U.S. stock index futures fell on Monday as growing trade tensions between the United States and China kept investors on edge, with the latest threat involving a check on Chinese investments in U.S. technology firms.
The S&P 500 mini futures dropped 0.5 percent after a government official, with knowledge of the matter, said the U.S. Treasury Department was drafting curbs that would block firms with at least 25 percent Chinese ownership from buying U.S. companies with "industrially significant technology".
Chipmakers and U.S.-listed Chinese companies were among the most traded stocks in early premarket trading on Monday. Advanced Micro Devices fell 0.4 percent and Alibaba dropped 1.7 percent.
The move marks another escalation of President Donald Trump's trade conflict with China, which has sent ripples across financial markets and threatened to dent global growth.
The Dow Jones Industrial Average lost 2 percent last week, posting its weakest weekly performance since late March, after Trump threatened to impose a 20 percent tariff on all European Union car imports. The EU — which has promised retaliatory measures on motorcycle maker Harley-Davidson , bourbon and other products — vowed to respond.
Harley fell 2.7 percent on Monday after the company forecast additional costs between $30 million and $45 million for the rest of 2018, due to EU tariffs.
Dow e-minis were down 166 points, or 0.67 percent and Nasdaq 100 e-minis were down 60.25 points, or 0.83 percent.
Brent crude prices, which provided support to the equity markets last week, fell more than 1.5 percent as investors prepared for an extra 1 million barrels per day in output to hit the markets after OPEC and its partners agreed to raise production.
In economic data, a Commerce Department report is expected to show new home sales rose 1.5 percent to a 667,000-unit rate in May. The report is due at 10:00 a.m. ET.
Among early gainers was Campbell Soup, which jumped 6.2 percent after a New York Post report that Kraft Heinz was considering buying the company.
Education Realty Trust Inc rose 1.2 percent after the company said it would be acquired by an affiliate of Greystar Real Estate Partners for about $4.6 billion, including debt. (Reporting by Sruthi Shankar in Bengaluru; Editing by Shounak Dasgupta)