The administration of U.S. President Joe Biden has asked Congress to approve the sale of 45,000 shells for Israel's Merkava tanks for use in its offensive against Hamas in Gaza, according to four sources familiar with the matter, including a U.S. official and a former U.S. official.

The request is being made even as concerns grow about the use of U.S. weapons in a war that has killed thousands of civilians in the Palestinian enclave since Israel responded to an attack on Oct. 7 by Hamas militants.

The potential sale, worth more than $500 million, is not part of Biden's $110.5 billion supplemental request that includes funding for Ukraine and Israel. It is under informal review by the Senate Foreign Relations and House of Representatives Foreign Affairs committees, which allows members the privilege to stall the sale, or have informal discussions with the administration about concerns.