Sudan has agreed to allow international human rights groups to visit refugee camps in the troubled Darfur region, UK Foreign Secretary Jack Straw says.
Human rights groups have been promised access to the refugees
He met officials in Khartoum and has now arrived in Darfur, where a million people have fled attacks by militiamen.
Sudan has meanwhile rejected calls for African troops to be sent to Darfur to disarm rebels fighting Khartoum's rule.
The offer was made by Nigerian leader Olusegun Obasanjo, who is hosting peace talks between the rebels and Sudan.
Mr Straw's visit to Sudan comes a week before the expiry of a UN deadline threatening Sudan with sanctions if it fails to ease the humanitarian crisis and find a political solution in Darfur.
After talks with his Sudanese counterpart, Mustafa Osman Ismail, on Monday, Mr Straw said he was pleased by Khartoum's pledge to allow the British offices of rights groups Amnesty International and Human Rights Watch access to Darfur.
More than 1m displaced
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 said Britain had no plans to deploy
troops to Darfur, but was prepared to support an African Union military presence
in the region.
Mr Straw has said he is visiting Sudan to try to get Khartoum to do more to curb the Arab Janjaweed militia's harassment of the refugees.
The UN has accused the Janjaweed of killing an estimated 50,000 Darfurians in an 18-month reign of terror.
More than a million people have been forced to flee their homes to escape the fighting, which escalated last year after Darfurian rebels took up arms against Khartoum.
Sudan's government denies the charge that it used the Janjaweed to quell the rebel uprising and has promised to disarm the militia.
At peace talks between the rebels and Khartoum, Sudan rejected calls by Nigerian President Olusegun Obasanjo for a large deployment of African soldiers to help disarmament in Darfur.
The suggestion was seemingly endorsed by Mr Straw, who said on Monday that Britain would help finance such a move.
More than a million people have fled their homes in Darfur
But Sudan's agriculture minister and top representative at the talks, Mazjoub al-Khalifa, dismissed the offer, saying, "I don't think there is a need for this".
He said it was the role of "the government of Sudan and the security forces" to "simultaneously" disarm the anti-government rebels as well as the Janjaweed militia.
However, rebel leaders attending the peace talks in the Nigerian capital, Abuja, criticised Mr Khalifa's position.
"There is no way we can let our enemies disarm us," said Abubakar Hamid Nour of Justice and Equality Movement (JEM). "They are still killing and bombing us."
The BBC's Anna Borzello in Abuja says there is so far little sign of optimism at the talks, which its organisers, the African Union, hopes will prove the continent is capable of solving its own problems.
Previous talks collapsed in July when the rebels walked out after the government refused to meet their terms.