WASHINGTON - US additional tariffs on imports of consumer electronics products from China would have a "substantial negative impact" on American consumers, even after accounting for alternative sources of supply, said a US consulting firm.

Washington D.C.-based company Trade Partnership Worldwide LLC said this in a report as the White House is threatening to impose additional tariffs of 25 percent on $300 billion in goods from China, including cell phones, laptops and tablets.

In the report prepared for the US Consumer Technology Association on Monday, the consulting firm estimated that if the new tariffs were imposed, the cost of cell phones imported from China would rise by 22 percent in the United States.

Also, the overall US prices for cell phones would rise by 14 percent, or nearly $70 for the average retail price of a cell phone today, which will reduce the country's overall purchases by 28 percent, according to the report.

American consumers would pay over $8.1 billion more for cell phones and it will be a net loss of $4.5 billion for the US economy even after accounting for new tariff revenue, according to the report.

Plus, laptops and tablets will also see hikes across the board in both costs and prices. The cost of those imports from China will increase 21 percent while overall US prices will rise by 19 percent, or about $120 for the average retail price of a laptop today and about $50 for a tablet today.

American consumers would pay over $8.2 billion more for laptops and tablets and it will be a net $3.6 billion loss for the US economy even after accounting for new tariff revenue, according to the report.

The report also showed that shifting the supply to other countries will be difficult and cost a significant amount of money, with the burden carried mostly by US consumers.

China accounted for about 75 percent of the total cell phones and over 90 percent of the total laptops and tablets imported into the United States, according to Trade Partnership Worldwide.