WASHINGTON (Reuters) -U.S. President Donald Trump is expected to sign an executive order as early as next week that would revive an effort to decrease drug costs by tying the amount the government pays for some medicines to lower prices abroad, Politico reported on Wednesday, citing three people familiar with the matter.

The order is expected to direct aides to pursue the initiative, called most favored nation, for a selection of drugs within the Medicare program.

Reuters reported last month that drugmakers had been warned the Trump administration was considering such a policy, and that one expected the agency that runs Medicare to launch a pilot of the program.

The action, if implemented, would likely draw huge opposition from the pharmaceuticals industry. One drugmaker executive previously called the proposal the biggest "existential threat to the industry and U.S. biosciences innovation."

Shares of U.S. drugmakers fell on Wednesday in extended trading. Eli Lilly ( LLY ) led the declines with an over 3% drop in share price. Merck ( MRK ), Gilead Sciences ( GILD ) and Bristol Myers Squibb ( BMY ) stock fell roughly 2%.

Trump said on Tuesday the White House would make a big announcement related to the costs of drugs next week. "We're being ripped off, as you know, very badly being ripped off compared to the rest of the world," he said.

The U.S. pays the most for drugs in the world, often nearly three times that of other developed nations. Trump has said he wants to close that spread, but has not publicly specified how.

During Trump's first term, a court blocked his proposed international reference pricing program. The proposal five years ago was projected by his administration to save taxpayers more than $85 billion over seven years, cutting into U.S. annual spending of more than $400 billion on drugs.

Conservative think tank the America First Policy Institute in a widely circulated paper in March said the policy could be implemented within Medicare's drug price negotiations.

Former President Joe Biden's Inflation Reduction Act allows the government to negotiate the price of its costliest drugs.

The prices for the first 10 prescription drugs it negotiated were still on average more than double, and in some cases five times, what drugmakers had agreed to in four other high-income countries, Reuters previously reported.