Sudan has summoned senior UK and German diplomats to protest at "threats to national security" after the EU pushed for sanctions over the Darfur conflict.
There is not enough food to go around
Sudan's foreign minister said that UK statements about possible military intervention were "unacceptable".
The UN is set to discuss a resolution this week which would impose sanctions on the pro-government militia accused of mass killing and rape in Darfur.
More than a million people have fled their homes and up to 50,000 have died.
Aid agencies warn that thousands more could die in refugee camps from disease and starvation unless help arrives immediately.
An emergency meeting of Sudan's cabinet was called for Tuesday to discuss Darfur and the threat of sanctions.
"We regard this... as a threat to Sudan's national security and a violation of our country's national sovereignty," said Sudan's junior Foreign Minister Najuid al-Khair Abdul Wahab.
Up to 50,000 killed
More at risk from disease and starvation
Arab militias accused of ethnic cleansing
Sudan blames rebels for starting conflict
He also accused Germany of supporting Darfur rebels.
Sudan is lobbying to block the proposed UN sanctions.
China, Pakistan and Algeria are said to oppose immediate sanctions but US diplomats say they are confident that a majority of Security Council members back its draft resolution.
The pro-government Arab militias - or Janjaweed - are accused of ethnic cleansing against the black African population.
The Sudanese government denies backing the militiamen. In early July it promised to disarm them.
African leaders are set to seek an "African solution" to Darfur at a special summit in Ghana on Thursday, called by African Union (AU) chairman President Olusegun Obasanjo of Nigeria.
His envoy, former Nigerian leader Abdulsalami Abubakar, said he was "ashamed" to see what Africans had done to their fellow human beings, after visiting refugee camps in eastern Chad.
"I will report to the African Union chairman to lobby the African Union so that governments can speed up and increase their assistance," he said.
The AU has previously said it would deploy 300 troops to Darfur by the end of July.
A Rwandan military official said 150 Rwandan troops would leave for Darfur in early August but said their rules of engagement had still not been finalised, reports AFP news agency.
The EU ministers appealed to the Security Council "to pass a resolution with a view to taking further actions, including imposing sanctions, in case the government of Sudan does not immediately fulfil its obligations and commitments".
"There is no indication that the government of Sudan has taken real and provable steps to disarm and neutralise the armed militia, including the Janjaweed," their statement after talks in Brussels said.
The EU also agreed to send extra funds worth more than $30m to ease the humanitarian crisis.
Ministers urged the Sudanese government to admit more aid workers to provide emergency food and shelter for the people displaced in the region.
In neighbouring Chad, aid workers are continuing efforts to distribute supplies in two camps where operations were suspended for several days last week because of violence.
Relief agencies say more international help is required. France, which has an air base in the Chadian capital, Ndjamena, is coming under pressure to do more.
French Foreign Minister Michel Barnier is currently heading for Darfur, via a stop in Chad.