US Secretary of State Condoleezza Rice has demanded and received an apology after US officials and journalists were manhandled by Sudanese security staff.
Rice: "They had no right to manhandle my staff and the press"
The incidents happened as Ms Rice met President Omar al-Beshir at his Khartoum residence.
Reporters and some US officials were initially prevented from entering the meeting room by security staff.
Those who then tried to ask questions about the troubled Darfur region of Sudan were forcibly removed.
Attempts were made to seize the tape recorder of at least one journalist.
Ms Rice is now visiting refugees in Darfur after the talks with Mr Bashir, and is due to hold discussions about sexual violence against women refugees.
She has urged the new government in Sudan to take more decisive action to end the violence.
At least 180,000 people have died and about two million people have been forced from their homes in the two-year conflict in Darfur, blamed mainly on the pro-government Janjaweed militias.
Speaking after the incidents at the presidential palace, Ms Rice demanded an apology.
"It makes me very angry to be sitting with their president and have this happen," she told reporters.
"They had no right to manhandle my staff and the press."
State department spokesman Sean McCormack later said that Sudanese Foreign Minister Mustafa Osman Ismail had telephoned Ms Rice "apologising for the treatment of our delegation and the press corps accompanying the secretary".
And Ambassador Khidair Haroun Ahmed, head of the Sudanese mission in Washington, said: "Please accept our apologies. This is not our policy."
The BBC's Jonathan Beale, who is travelling with Ms Rice, says the row is very bad news for a new government which is trying to say that it is becoming more open and introducing press freedom.
The US has described the violence in Darfur as genocide.
But Ms Rice said she hoped stability could be restored in Sudan following a peace accord in the separate conflict in the south and the creation of a new unity government.
She said she was willing to proclaim a "new day" with the new government, but added that she expected more decisive movement to end the crisis in Darfur.
"We don't rely on words, we rely on actions. We have gotten some help from the Sudanese government - but by no means enough," she said.
Ms Rice's visit to a Darfur refugee camp will coincide with the arrival of hundreds of Rwandan soldiers, who will join an African Union (AU) peacekeeping force.
On Wednesday, the head of the AU force said that security had improved in Darfur, with no major attacks since January and a decrease in low-level skirmishes.
But US aid official Andrew Natsios said: "The major reason for that, frankly, is there are not many villages left to burn down and destroy."
The United Nations estimates that 2,000 Sudanese villages have been completely or partially destroyed.