Khartoum - The United States has warned Americans about travelling to Sudan given the "risks of terrorism" in the African country, prompting an angry response from Khartoum on Friday.The US Department of State's warning comes just days after Washington lifted its 20-year-old trade embargo imposed on Khartoum, citing Sudan's increased cooperation with US intelligence agencies in combatting terrorism.In a statement posted on the website of Washington's embassy in Khartoum, the US Department of State said that US citizens should avoid all travel to the five Darfur states, and to the states of Blue Nile and South Kordofan.It said Americans should also "consider carefully before planning travel to other areas of Sudan due to the risks of terrorism, armed conflict and violent crime"."Terrorist groups are present in Sudan and have stated their intent to harm Westerners and Western interests through suicide operations, bombings, shootings and kidnappings," the advisory said."Violent crimes targeting Westerners, including kidnappings, armed robberies, home invasions, and carjacking can occur anywhere in Sudan, but are particularly prevalent in Darfur states."The region of Darfur, and the two states of Blue Nile and South Kordofan, have witnessed brutal fighting between Sudanese forces and rebels for years that has killed tens of thousands of people and displaced millions.Washington's warning on Thursday comes just days after it lifted its trade embargo that was imposed on Khartoum in 1997.US officials have said that a key element in lifting the sanctions had been Khartoum's growing support to US intelligence agencies in combatting terrorism.Washington's warning triggered an angry response from Khartoum on Friday, with the foreign ministry urging the United States to stop issuing such "negative warnings"."The warning is contradictory to all the appreciation offered by senior US officials for Sudan's efforts in combatting terrorism," the ministry said."The ministry is calling on the United States to take the bilateral relations to a positive level and to stop issuing such negative warnings."Although Washington has lifted the sanctions that were imposed for Khartoum's alleged support for Islamist militant groups, it has still kept Sudan on its list of "state sponsors of terrorism".