Jared Kushner speaks during the Time 100 Summit event in New York on Tuesday. Don Emmert / AFP

US President Donald Trump's son-in-law Jared Kushner said on Tuesday that he would present his long-awaited Middle East peace proposal around June and that it would include a "robust business plan" for the Palestinians.

Kushner, speaking at a forum of Time magazine, said he had hoped to offer the proposal late last year but that Israeli Prime Minister Benjamin Netanyahu then called elections and still needs time to form a coalition.

"Once that's done we'll probably be in the middle of Ramadan, so we'll wait until after Ramadan and then we'll put our plan out," said Kushner, a senior advisor to Trump, referring to the Muslim fasting month which ends in early June.

Kushner's impending plan has already been met with deep skepticism from the Palestinians, who say Trump cannot be an honest broker after he took the landmark step of recognising bitterly disputed occupied Jerusalem as Israel's capital.

But Kushner, whose own role has been questioned due to his longstanding family ties with Netanyahu, said he remained hopeful that his "unconventional approach" would bear fruit.

He declined to answer if the plan would include longstanding US support for a Palestinian state, after hints by the administration that it would not, but said it would include investment to boost the Palestinian economy.

"Our focus is really on the bottom up, which is how do you make the lives of the Palestinian people better, what can you resolve to allow these areas to become more investable?" he said.

"We deal with all the core status issues because you have to do it, but we've also built a robust business plan for the whole region," he said.

Kushner also said the plan would address Israel's concerns over security.

"I think that what we do is something that allows for Israel to maintain security, but there will be tough compromises for both," he said.

Netanyahu in his election campaign had vowed to annex parts of the West Bank where Israeli settlers live, a prospect that would doom longstanding Palestinian hopes of a state.

Agence France-Presse