(Reuters) -Billionaire fund manager Bill Ackman, who endorsed Donald Trump's run for president, ratcheted up his pleas with Washington to hit pause on tariffs to stave off "a major global economic disruption."

While tariffs are an essential tool for eliminating "unfair trading practices" by partners, implementing them without allowing time for agreements will do "unnecessary harm," he said in a post on social media platform X on Tuesday.

A pause of 30, 60, or 90 days will prevent "a major global economic disruption that would harm the most vulnerable companies and citizens of our country," Ackman added.

The comments reflect growing alarm in corporate America, as the new trade barriers raise fears of global retaliation, a potential trade war, renewed inflation and an eventual recession.

Ackman is among a number of high-profile executives who have expressed concerns over Trump's new tariff plan. If the "asymmetric tariff deals" are not resolved, it can lead to an "economic nuclear winter", he has said.

The policy has also created tensions within Trump's inner circle. Elon Musk, the Tesla CEO who is leading the administration's Department of Government Efficiency, has lashed out at Peter Navarro, Trump's top trade adviser who is widely seen as the architect of the tariff plans.

In the two sessions after the tariff decision was unveiled on April 2, the S&P 500 tumbled 10.5%, erasing nearly $5 trillion in market value, marking its most significant two-day loss since March 2020. Wall Street's main indexes, however, clawed back some of the losses on Tuesday. [.N]

(Reporting by Niket Nishant in Bengaluru; Additional reporting by Svea Herbst-Bayliss; Editing by Anil D'Silva)