President Recep Tayyip Erdogan said it was "out of the question" for Turkey to support the US economic plan for Palestinians, in comments published on Monday.
The White House plan revealed last week calls for $50 billion in investment over 10 years in the Palestinian territories and their Arab neighbours.
"It is out of the question for us to approach this issue positively," Erdogan told journalists aboard his plane returning from the G-20 summit in Japan, according to pro-government daily Yeni Safak.
Listing a slew of projects to develop roads, border crossings, power generation and tourism, the US framework sets an optimistic goal of creating one million Palestinian jobs.
US President Donald Trump's administration has however hinted that its political plan -- due later in the year -- will not mention a Palestinian state, abandoning long-standing US policy.
The Palestinian Authority and its rival Hamas have both denounced the economic initiative, saying it amounts to a bid by the unabashedly pro-Israel Trump to buy off their demands for an independent state.
Erdogan is a vocal advocate of the Palestinian cause, and strongly opposed the US decision to move its Israeli embassy to Jerusalem last year.
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