By Daphne Psaledakis

WASHINGTON A bipartisan group of U.S. lawmakers plans to introduce a bill on Thursday intended to bar the U.S. government from recognizing Bashar al-Assad as Syria's president and enhance Washington's ability to impose sanctions in a warning to other countries normalizing relations with Assad.

The bill, seen by Reuters, would prohibit the U.S. federal government from recognizing or normalizing relations with any government in Syria led by Assad, who is under U.S. sanctions, and expands on the Caesar Act, a U.S. law that imposed a tough round of sanctions on Syria in 2020.

The bill comes after Arab states turned the page on years of confrontation with Assad on Sunday by letting Syria back into the Arab League, a milestone in his regional rehabilitation even as the West continues to shun him after years of civil war.

Regional countries - including Saudi Arabia, Qatar and others - had for years supported anti-Assad rebels, but Syria's army - backed by Iran, Russia and allied paramilitary groups - regained most of the country. The icy ties with Assad began to thaw more quickly after devastating earthquakes in Syria and Turkey in February.

The United States has said it will not normalize ties with Assad and its sanctions remain in full effect.

The bill will be introduced by House of Representatives Foreign Affairs Committee Chairman Michael McCaul, congressman Joe Wilson, the chair of the Subcommittee on the Middle East, North Africa, and Central Asia; and Democrats Steve Cohen and Vicente Gonzalez, among others, a senior congressional staffer who worked on the bill told Reuters.

The legislation is a warning to Turkey and Arab countries that if they engage with Assad's government, they could face severe consequences, the staffer, said speaking on condition of anonymity.

"The readmission of Syria to the Arab League really infuriated members and made clear the need to quickly act to send a signal," they said.

The bill's provisions include a requirement for an annual strategy from the secretary of state for five years on countering normalization with Assad's government, including a list of diplomatic meetings held between Syria's government and Turkey, the United Arab Emirates, Egypt and others.

The bill would also clarify the applicability of U.S. sanctions on Syrian Arab Airlines and another carrier, Cham Wings. Under the proposed bill, countries that allow the airlines to land would face sanctions against that airport, the staffer said.

If passed, the bill would also require a review of transactions, including donations over $50,000 in areas of Syria held by Assad's government by anyone in Turkey, the UAE, Egypt and several other countries.

(This story has been refiled to delete redundant mention of congressman Joe Wilson in paragraph 6)

(Reporting by Daphne Psaledakis; editing by Jonathan Oatis)