Hillary Clinton, the US secretary of state, is to formally announce the funding at a donor conference in Egypt next week, one US official told the Reuters news agency on Monday.
The money, which would need to be approved by the US congress, is to be distributed through the UN and other bodies and not via Hamas, the Palestinian group which governs Gaza, said one of the officials, who asked to remain anonymous.
The same official said the pledge was a mix of money already earmarked for the Palestinians and some new funding.
Rob Reynolds, Al Jazeera's senior Washington correspondent, said the administration of Barack Obama, the US president, had not moved towards engaging directly with Hamas but had modified some of its language towards dealing with Palestinians in Gaza.
It was prepared to mention Palestinian suffering without directly linking it to the actions of Hamas, our correspondent said.
The US has repeatedly said it will not hold talks with Hamas unless it recognises Israel, renounces violence and recognises previous Palestinian peace agreements.
In December, the administration of George Bush, Obama's predecessor, said it would give $85m to the UN agency that provides aid to Palestinian refugees in the West Bank, Gaza, Jordan, Lebanon and Syria....