WASHINGTON, Dec 4 (Reuters) - U.S. President Joe Biden and Russian President Vladimir Putin will hold a video call on Tuesday, with the two leaders set to discuss the tense situation in Ukraine.

"Biden will underscore U.S. concerns with Russian military activities on the border with Ukraine and reaffirm the United States' support for the sovereignty and territorial integrity of Ukraine," White House spokesperson Jen Psaki said in a statement.

She said other topics would include "strategic stability, cyber and regional issues."

The two will also talk about bilateral ties and the implementation of agreements reached at their Geneva summit in June, the Kremlin said on Saturday.

"The conversation will indeed take place on Tuesday," Kremlin spokesman Dmitry Peskov told Reuters. "Bilateral relations, of course Ukraine and the realization of the agreements reached in Geneva are the main (items) on the agenda," he said.

The exact timing of the call was not disclosed.

More than 94,000 Russian troops are believed to be massed near Ukraine's borders. Ukraine Defense Minister Oleksii Reznikov said on Friday that Moscow may be planning a large-scale military offensive at the end of January, citing intelligence reports. U.S. officials have come to similar conclusions, they said.

Biden, meanwhile, has rejected Russian demands for security guarantees in the region.

"My expectation is we're going to have a long discussion with Putin," Biden told reporters on Friday as he departed for a weekend trip to Camp David. "I don't accept anybody's red lines," he said.

The U.S. president said he and his advisers were preparing a comprehensive set of initiatives aimed at deterring Putin from an invasion. He did not give further details, but the administration has discussed partnering with European allies to impose more sanctions on Russia.

U.S. Defense Secretary Lloyd Austin separately said that Washington was committed to ensuring that Ukraine had what it needed to protect its territory.

Austin added that there was a lot of space for diplomacy and leadership to work on Ukraine.

At the same conference, James C. McConville, chief of staff of the U.S. Army, on Saturday referred to estimates of 95,000 to 100,000 Russian troops on the border with Ukraine.

"I don't know what they are going to do, but I am very, very concerned," McConville said.

Moscow accuses Kyiv of pursuing its own military build-up. It has dismissed as inflammatory suggestions that it is preparing for an attack on its southern neighbor and has defended its right to deploy troops on its own territory as it sees fit.

U.S. officials say they do not know yet what Putin's intentions are, including whether Putin has made a decision to invade Ukraine.