WASHINGTON, May 20 (Reuters) - The United States and Saudi Arabia are close to a final agreement on a bilateral defense pact after the U.S. national security adviser made significant progress in talks with the Saudis over the weekend, the White House said on Monday.

White House national security spokesperson John Kirby said the two sides are "closer than we've ever been" on a bilateral agreement that is now "near final."

U.S. and Saudi negotiators are seeking to complete work on a bilateral accord expected to call for formal U.S. guarantees to defend the kingdom as well as Saudi access to more advanced U.S. weaponry, in return for halting Chinese arms purchases and restricting Beijing’s investment in the country.

Negotiators have been discussing U.S. sales of F-35 fighter jets and other weapons to the Saudis as part of the deal, a U.S. official said.

The potential sale of the F-35s to the Saudis was not guaranteed for a variety of reasons, but its inclusion in the discussions was significant because Riyadh has desired the stealthy fighter jet for years. Any deal must satisfy a longstanding agreement with Israel that U.S. weapons sold in the region must not impair Israel's "qualitative military edge," guaranteeing U.S. weapons furnished to Israel are "superior in capability" to those sold to its neighbors. The U.S. Senate Foreign Relations and House of Representatives Foreign Affairs committees, whose members have criticized the kingdom's role in civilian deaths in Yemen, have the right to review, and block, weapons sales under an informal review process. Lockheed Martin Corp (LMT.N), opens new tab, which makes the jet, referred a request for comment to the government.

The defense pact would be short of a NATO-style agreement, the official said.

White House national security adviser Jake Sullivan held talks with Saudi Crown Prince Mohammed bin Salman and other Saudi officials over the weekend where progress was made, Kirby said.

A second U.S. official said, "We are very close to an understanding on the major elements between us."

"We of course will also have to then work on pieces that relate to the Israelis and Palestinians, which is a critical component of any potential normalization deal," the official said.

The U.S.-Saudi security accord is also expected to involve sharing emerging technologies with Riyadh, including artificial intelligence.

Once the deal is completed, it would be part of a broad deal presented to Israeli Prime Minister Benjamin Netanyahu to decide whether to make concessions to secure a deal normalizing relations with Saudi Arabia.

Kirby said the timing of a U.S.-Saudi deal was unclear. He said an ultimate objective for Biden is a Palestinian state, but with Israel at war with the Palestinian militant group Hamas in Gaza, no deal on a state is likely any time soon.

"Of course, the president remains committed to a two-state solution. He recognizes that you know, that's not something we're going to see any anytime in the future," he said.

Photo from Reuters