US President Joe Biden

Nearly 1800 people signed a letter calling on him to release documents that they believe implicate officials from Saudi Arabia in the plot.

They say that if he refuses, he should not attend ceremonies next month to commemorate the 20th anniversary.

Nearly 3000 people died on 9/11.

The attacks were committed by the Al Qaeda terror group, investigators say, and triggered the US invasion of Afghanistan. Fifteen of the 19 plane hijackers were Saudi nationals.

The international community has called for an end to the escalating conflict.

Earlier, Israeli air strikes in Gaza killed 10 people in a refugee camp and, separately, destroyed a building that housed foreign media organisations.

Hundreds of Palestinian rockets were fired into Israel, causing one death.

The UN Security Council will meet on Sunday to discuss the situation. US envoy Hady Amr has arrived in Tel Aviv to take part in talks with Israeli, Palestinian and UN officials, and reinforce what US diplomats said was the need for a "sustainable calm".

The conversation included a discussion about the ongoing opposition protests in Russia and an extension of the last remaining US-Russia nuclear arms pact.

Mr Putin congratulated the new US president on winning the election, according to a Russian statement.

Both parties said they agreed to maintain contact moving forward.

Former US President Donald Trump sometimes undercut his own administration's tough posture on Russia and was accused of being too deferential to Mr Putin.

"Democracy has prevailed," he said after taking the oath of office from Chief Justice John Roberts.

Donald Trump - who has not formally conceded the presidency to Mr Biden - snubbed the inauguration ceremony, in a departure from longstanding precedent.

The new president has announced a raft of measures reversing Trump policies.

Kamala Harris was sworn in as vice-president ahead of Mr Biden. She is the first woman - and the first black and Asian-American person - to serve in a role, a heartbeat from the presidency.