Thousands of Palestinians have rallied in the besieged Gaza Strip to protest against US President Donald Trump's imminent announcement of a plan to resolve the Israeli-Palestinian conflict.

Raising a banner that read "Palestine is not for sale", demonstrators on Tuesday burned photos of Trump and Israeli Prime Minister Benjamin Netanyahu.

More protests are expected after the US president announces details of his Middle East plan later in the day.

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On Monday, Trump held separate meetings with Netanyahu and his election rival, Benny Gantz, in Washington, DC, over the long-delayed Middle East plan which has been kept secret to date.

An Israeli military spokesman said troops had been sent to reinforce the occupied West Bank's Jordan Valley, an area which Netanyahu has pledged to partially annexe.

Protest against the alleged "Deal of the Century" in Gaza City. pic.twitter.com/T2zPREm4Kz — Palestine Play (@PalestinePlay) January 28, 2020

Palestinian leaders have already rejected the plan which they decried as an attempt by the US and Israel to "finish off the Palestinian cause".

In a rare show of unity, leaders from Hamas, who govern Gaza, were invited to an emergency meeting held by Palestinian President Mahmoud Abbas in the West Bank city of Ramallah.

"When we are united, neither Netanyahu nor Trump dares to take away our rights," said senior Hamas official Khalil al-Hayya.

Palestinians take part in a protest against Trump's Middle East plan in Gaza [Ibraheem Abu Mustafa/Reuters]

Meanwhile, Husam Zomlot, head of the Palestinian mission to the United Kingdom, described the plan as "political theatre".

"It is not a peace deal. It is the 'bantustan-isation' of the people of Palestine and the land of Palestine. We will be turned into bantustans," Zomlot was quoted as saying by Reuters News Agency, referring to the nominally independent black enclaves in apartheid-era South Africa.

"January 28, 2020, will mark the official legal stamp of approval of the United States for Israel to implement a full-fledged apartheid system," he said.

Palestinians fear Trump's blueprint will dash their hopes for an independent state in the occupied West Bank, Gaza and East Jerusalem - areas Israel captured in the 1967 Middle East War - by permitting Israel to annexe large chunks of occupied land including blocs of Jewish settlements.

"They [Palestinians] have not been consulted, they haven't been spoken to and they certainly don't agree with the leaks and all the speculation of what is in the plan," said Al Jazeera's Stefanie Dekker, reporting from Gaza.

"Many people we spoke to say it's more about the West Bank and the annexation of the capital East Jerusalem."