More than 100,000 people have now been killed in the Syria civil war, UN leader Ban Ki-moon said Thursday as he appealed for new efforts to convene a peace conference.
The UN chief and US Secretary of State John Kerry told reporters before talks at the UN headquarters that there could be no military solution to the 28-month-old conflict.
While Syrian activists say the death toll is well over 100,000, the UN had been more cautious. One month ago it said about 93,000 had died.
But on Thursday, Ban said: "More than 100,000 people have been killed, millions of people have either been displaced or become refugees in neighboring countries.
"We have to bring this to an end. The military and violent actions must be stopped by both parties, and it is thus imperative to have a peace conference in Geneva as soon as possible."
The United States and Russia vowed in May to press for a follow up to a peace conference held in Geneva last year, which set out a transition plan.
However, divisions between Syrian opposition groups and diplomatic hurdles thrown up by President Bashar al-Assad's government have blocked efforts to call a new meeting.
Syrian National Coalition president Ahmad Jarba is in New York on Thursday and was to hold talks with Kerry ahead of a meeting with UN Security Council envoys on Friday.
Kerry said there are "enormous levels of suffering, suffering that is growing by the day, which requires all of us to work even harder to try to bring about peace negotiations."
He added: "There is no military solution to Syria, there is only a political solution. That will require leadership in order to bring people to the table."
Kerry said he spoke Wednesday with Russia's Foreign Minister Sergei Lavrov. "We remain committed to the effort to bring the parties to a Geneva II, to implement Geneva I, and we will try our hardest to make that happen as soon as is possible."
Ban has previously said he would like a peace conference in September. But UN diplomats say the conflict is now so bitter that they doubt the two sides can be brought to the negotiating table.
"The chances of a meaningful peace conference are now zero, but the US and UN can't admit that," said Richard Gowan of New York University's Center for International Cooperation.
"If Ban gave up on the conference proposal, it would underline that the UN no longer has a diplomatic role in Syria," Gowan said.
"If Kerry gives up the conference idea he'll lose some more personal credibility and, more importantly, fuel renewed calls for a US intervention in Syria," he added.
US President Barack Obama's plan to provide vetted Syrian rebels with weapons and strategic military aid is gaining traction in Congress, according to US lawmakers.
The United States is currently providing humanitarian and non-lethal military aid to rebel groups.
The US government promised an expansion of military aid to Syria's rebel forces in June after accusing Assad's forces of using chemical weapons, but such aid has yet to be disbursed.
Britain, France and other European states say they are also ready to step up military aid to rebel forces but insist no decision has yet been taken.
Ban also said that two UN envoys had completed talks in Damascus on seeking access for UN inspectors to Syria for an inquiry on the use of chemical weapons.
Ake Sellstrom, head of the inquiry, and Angela Kane, the UN high representative for disarmament, arrived in Damascus on Tuesday. "They are coming out of Syria now, we will get the report soon," Ban said.