Washington will toughen enforcement of existing sanctions; bar another 31 companies, including oil exporters, from US trade and financial dealings; and take aim at two senior Sudan government officials, they said.
From a US perspective, a new UN resolution would apply new multilateral financial sanctions against Sudan and the three newly targeted individuals and expand an existing arms embargo from individuals operating in Darfur to any sales to Sudan's government, a US official said.
The Darfur conflict has cost at least 200,000 lives and forced more than 2m people from their homes, according to the UN, though Sudan contests those estimates, saying 9,000 people have died.
A Sudanese official said on Tuesday the expanded US sanctions Darfur would be neither justified nor timely, but would nevertheless not affect Sudan's response to a hybrid force proposal for Darfur.
Mutrif Siddig, a senior official in the foreign ministry, said: "I think these sanctions are not justified. It is not timely."
For his part, China's special envoy on Darfur said his country's investment in Sudan can help stop the bloodshed there while sanctions and pressure advocated by some other countries will only complicate the situation.
Khartoum's hand has been strengthened by China, which has opposed US-led plans within the Security Council to use sanctions to force al-Bashir to accept a UN deployment.
China openly supplies arms to Sudan and buys more than half of the African state's oil output.
Bush says in remarks prepared for delivery from the White House diplomatic reception room: "President Bashir's actions over the past few weeks follow a long pattern of promising co-operation while finding new methods of obstruction."
|The conflict in Darfur has displaced more than|
two million people from their homes [EPA]
Washington's sanctions will be effective from Tuesday even though US diplomats are launching an all-out effort to win support for a new UN resolution, including efforts to overcome possible Chinese resistance, a senior US official said.
Separately, France has proposed opening a humanitarian corridor through Chad to bring relief to victims of the Darfur conflict.
Bernard Kouchner, the French foreign minister, made the announcement late on Monday in in the northern German city of Hamburg. After talks with his Chinese counterpart, he said: "We are mulling several options, including securing a humanitarian corridor from Chad."
On Tuesday, reacting to news of the planned US sanctions, Liu Guijin, who took up the new post of special representative to African affairs earlier this month, said: "The Darfur issue and issues in eastern Sudan and southern Sudan are caused by poverty and underdevelopment.
"Only when poverty and underdevelopment are addressed will peace be there in Sudan.
"The co-operation between China and Sudan is helpful for the development of Sudan's economy and will fundamentally help Sudan to address the conflicts and wars in Sudan.
"Wilful sanctions and simply applying pressure are not conducive to the solution of the problem and will only make the issue more complicated."