UNITED NATIONS: The United States Tuesday urged the divided U.N. Security Council to back an arms embargo and sanctions against South Sudan after the U.N. envoy reported that the war there is worsening.

U.S. Ambassador Nikki Haley told the council that U.N. demands for a ceasefire, access for aid workers and a return to political talks had been "totally ignored" by President Salva Kiir's government.

"I call on this council to move forward with the tools available to it, such as with further sanctions and an arms embargo, or the violence and atrocities will continue," Haley said.

"We must tell the South Sudanese government that we are not going to put up with this anymore."

France and Britain backed the U.S. call for tougher measures, but Russia said there was no need for an arms embargo and China urged the council to be more "positive" in its approach to South Sudan.

The previous US administration failed in December to win support at the council for an arms embargo and sanctions, with Russia, China, Japan and Egypt among eight countries that abstained in a vote on the measures.

Haley's remarks indicated that the new U.S. administration would try again to push for an end to weapons sales and sanctions on those who undermine peace efforts.

"If you want to continue to see starvation in South Sudan, doing nothing is exactly what you need to keep doing," said the U.S. envoy.

Helping the people of South Sudan is "not about hope," "not about wishes," she added. "That's about action, and I call on the Security Council to act."

U.N. envoy David Shearer earlier told the council that the situation was dire after more than three years of war.

"Virtually no part of the country is immune from conflict. Yet there has been no concerted effort by any party to adhere to a ceasefire," said Shearer.

"Instead, over the past month, we are seeing an intensification of the conflict."

After gaining independence from Sudan in 2011, South Sudan descended into war in December 2013, leaving tens of thousands dead and more than 3.5 million people displaced.

In February, South Sudan and the United Nations formally declared a famine in parts of northern Unity State affecting 100,000 people, a disaster that U.N. officials said was "man-made" and could have been averted.