(Corrects Sudanese ambassador's name in fifth paragraph)
By Louis Charbonneau
UNITED NATIONS, June 12 (Reuters) - The United States on Thursday condemned recent attacks by the Sudanese government's Rapid Support Forces on civilians in the Blue Nile and South Kordofan states, saying they have been deliberately targeting schools and hospitals.
The statement from U.S. Ambassador to the United Nations Samantha Power came just days after a coalition of 45 organizations providing humanitarian aid or supporting peace efforts in Sudan wrote to the U.N. Security Council, African Union and Arab League demanding an end to attacks on civilians.
"The United Sates condemns in the strongest possible terms attacks by the Government of Sudan and its Rapid Support Forces (RSF) against civilians in South Kordofan and Blue Nile," Power said.
"Since April, not only have ground attacks on, and the shelling of, civilian populations increased, but the Government of Sudan has intensified its air campaign, dropping hundreds of barrel bombs and other ordinance on Sudanese towns and villages, deliberately targeting hospitals and schools."
Sudan's U.N. Ambassador Rahamtalla Mohamed Osman Elnor did not respond immediately to a request for comment.
Last month the U.N. Office for the Coordination of Humanitarian Affairs said fighting between Sudanese military and SPLM-N rebel forces in South Kordofan and Blue Nile intensified in April-May 2014 as the government pressed ahead with its "Decisive Summer" military campaign to end armed rebellions.
Power said the increased violence has displaced or severely affected about 1.2 million people. She said aid groups working in Sudan have accused the RSF of looting and destroying food and water supplies in areas recaptured by rebels.
The government has denied aid access to rebel areas of South Kordofan and Blue Nile for almost three years.
"We have also seen these tactics used recently in Darfur, displacing over 300,000 people this year," Power said, referring to Sudan's remote western region where the United Nations says as many as 300,000 people have been killed since 2003.
In their letter to the Security Council, Arab League and African Union's Peace and Security Council, aid groups said the government's bombing campaign has escalated to levels unseen in the years of fighting in South Kordofan and Blue Nile.
"These unprecedented attacks represent the largest sustained bombardment of civilian targets in the three year history of the conflict," the letter said. "They have spread terror and sent families into hiding in caves and foxholes, too afraid to plant their crops."
The coalition of aid groups called on the United Nations, Arab League and African Union to press for an end to the Sudanese military campaign, launch an independent investigation into "breaches of international human rights and humanitarian law" and hold accountable anyone responsible.
Earlier this year, John Prendergast, a former U.S. State Department official and co-founder of the Enough Project anti-genocide group, said the RSF was the latest incarnation of Janjaweed militia fighters who massacred civilians and torched homes across Darfur in 2003. (Reporting By Louis Charbonneau. Editing by Andre Grenon)