Israel's parliament is to vote on a controversial bill that seeks to retroactively legalise 4,000 settler homes built on privately owned Palestinian land in the occupied West Bank, a measure the attorney general has said is unconstitutional.

The bill has already passed the first reading in the Knesset, and will be heard two more times on Monday.

Al Jazeera's Imran Khan, reporting from West Jerusalem, said the bill is "incredibly controversial".

Unlike territory occupied by Israel under military rule, the "regulation bill" concerns land where Palestinians themselves own title deeds.

"It's their land. They can prove that it's their land," said Khan.

Experts in Israel say the bill violates Israeli and international law on settlements.

If the bill is passed, it would mark one of the few times in 50 years that the Knesset approved legislation concerning the occupied West Bank.

Avichai Mandelblit, Israel's attorney general and the government's top lawyer, opposes the bill and has vowed not to defend it in the Supreme Court.

He believes the bill is unconstitutional and may drag Israel to the International Criminal Court at the Hague.

The far-right Jewish Home party, a member of the governing coalition, is pushing for the legislation to be passed.

"Centrist and leftist parties, however, are all fiercely against the bill," our correspondent said. "They say it's effectively stealing Palestinian land."

Under the bill, Palestinian owners would be financially compensated by Israel, but could not sell their land.

Israeli Prime Minister Benjamin Netanyahu tweeted on Sunday that the law was designed to "regulate" settlement and "prevent recurrent attempts to harm the settlement enterprise".

Trump effect

The bill was likely to be debated "particularly in the second and third reading", said our correspondent, adding that the decision was expected to take hours.

"The green light is not coming so much from Israel, it's coming from the US," he added.

Israel recently approved a plan to build 2,500 new settlement homes in the West Bank, days after it accepted building permits for more than 500 settler homes in East Jerusalem.

The biggest settlement plan announced since 2013 came shortly after the inauguration of US President Donald Trump, with Israeli officials saying the permits had been held up until the end of Barack Obama's administration.

"The rules of the game have changed with Donald Trump's arrival as president," Meir Turgeman, Jerusalem's deputy mayor, has previously said. "We no longer have our hands tied as in the time of Barack Obama. Now we can finally build."

Turgeman has spoken of plans for about 11,000 homes in process for East Jerusalem.

The homes covered by the proposed legislation are in outposts built deep in the West Bank without Israeli government approval.

The new law would allow settlers to hold on to land if, as stated by the bill, they "innocently" took it - ostensibly without knowing the tracts were owned by Palestinians - or if homes were built there at the state's instruction.

Trump, who has expressed strong support for Israel, has pledged to recognise Jerusalem as Israel's "undivided" capital, and relocate the American embassy from Tel Aviv to Jerusalem, moves opposed by the Palestinian leadership.