At least 41 Palestinians were today killed by Israeli troops along the Gaza border, health officials said, as demonstrators streamed to the frontier on the day the US prepared to open its embassy in Jerusalem.

Protests intensified on the 70th anniversary of Israel's founding, with loudspeakers on Gaza mosques urging Palestinians to join a 'Great March of Return'. Black smoke from tyres burnt by demonstrators rose into the air at the border.

'Today is the big day when we will cross the fence and tell Israel and the world we will not accept being occupied forever,' Gaza science teacher Ali, who declined to give his last name, told Reuters.

'Many may get martyred today, so many, but the world will hear our message. Occupation must end,' he said.

Israeli troops killed 18 Palestinians, including a 14-year-old boy, and some 500 protesters were injured, at least 200 by live bullets, health officials said.

No Israeli casualties have been reported since the protests began on March 30.

The killings have drawn international criticism, but the US, which has angered the Palestinians and Arab powers by relocating its embassy to Jerusalem from Tel Aviv, has echoed Israel in accusing Gaza's ruling Hamas movement of instigating violence, an allegation it denies.

Later in the day, Israeli leaders and a US delegation including treasury secretary Steven Mnuchin and President Donald Trump's daughter and son-in-law, Ivanka Trump and Jared Kushner, were due to attend the opening of the embassy.

'What a moving day for the people of Israel and the State of Israel,' Israeli prime minister Benjamin Netanyahu said.

Jason Greenblatt, Trump's Middle East peace envoy, said on Twitter that 'taking the long-overdue step of moving our Embassy is not a departure from our strong commitment to facilitate a lasting peace deal. Rather, it is a necessary condition for it.'

But Palestinian prime minister Rami Hamdallah said Trump's recognition of Jerusalem as Israel's capital in December and the relocation of the embassy were 'blatant violations of international law'.

The Palestinians, who want their own future state with its capital in East Jerusalem, have been outraged by Trump's shift from previous administrations' preference for keeping the US embassy in Tel Aviv pending progress in peace efforts.

Those talks have been frozen since 2014. Other international powers worry that the US move could also inflame Palestinian unrest in the occupied West Bank, which Israel captured along with East Jerusalem in the 1967 Middle East war.

Israel's military dropped leaflets into the enclave today, warning Palestinians 'not to serve as a tool of Hamas' or approach or damage Israel's frontier fence.

But thousands of Palestinians massed at five locations along the line. Of the 35 people wounded by Israeli gunfire, four were journalists, the officials said.

The Israeli military says its troops are defending the border and firing in accordance with the rules of engagement.

'We are prepared to face the Hamas threats to disrupt the [embassy] festivities,' Israeli defence minister Avigdor Lieberman tweeted.

'My recommendation to the residents of Gaza: Don't be blinded by [Hamas's Gaza leader, Yehya Al-] Sinwar, who is sending your children to sacrifice their lives without any utility. We will defend our citizens with all measures and will not allow the fence to be crossed.'

The protests are scheduled to culminate on Tuesday, the day Palestinians mourn as the 'Nakba' or 'Catastrophe' when, in 1948, hundreds of thousands of them were driven out of their homes or fled the fighting around Israel's creation.

'Choosing a tragic day in Palestinian history [to open the Jerusalem embassy] shows great insensibility and disrespect for the core principles of the peace process,' Hamdallah wrote.

Most countries say the status of Jerusalem – a sacred city to Jews, Muslins and Christians – should be determined in a final peace settlement and that moving their embassies now would prejudge any such deal.

Additional reporting by Reuters.