Russian officials on Thursday dismissed a claim by the United States that Moscow has sent "thousands" of troops to fight alongside pro-Russian separatists in Ukraine.

"These figures, which are plucked out of the air, of course demoralize and disorientate the international community," foreign ministry spokesman Alexander Lukashevich said.

Ukraine on Thursday observed a day of mourning after 32 miners perished in a blast in a notoriously dangerous mine just a few kilometers from the frontline, where Kiev is reporting an increase in attacks by pro-Russian separatists.

Rescuers found the bodies of 32 miners in the Zasyadko mine, with one person unaccounted for, a day after a blast ripped through the shaft, emergency officials of the self-proclaimed Donetsk People's Republic said.

The Army leadership reportedly received confirmation from the concerned French authorities that they will start shipping $3 billion worth of weapons paid for by Saudi Arabia to the Lebanese military in April.

According to An Nahar newspaper published on Thursday, French officials contacted high-ranking military officials recently and informed them that the first batch of arms will be delivered soon.

Hillary Clinton, facing criticism over her exclusive use of a private email account while U.S. secretary of state, has called for her emails to be made public after Republicans subpoenaed the documents.

"I want the public to see my email. I asked State to release them. They said they will review them for release as soon as possible," Clinton said in a tweet late Wednesday night.

A California man who tried to travel to Syria last year has been charged with attempting to join the so-called Islamic state militant group, U.S. prosecutors announced Wednesday.

Adam Dandach, 21 -- also known as Fadi Fadi Dandach -- was charged with trying to provide support to a foreign terrorist group and making a false passport application statement to facilitate terrorism, they said.

The United States on Wednesday warned an offensive to retake control of the Iraqi city of Tikrit from Islamic State militants must not fuel sectarian tensions.

"It is important -- and (Iraqi) Prime Minister (Haider al-)Abadi himself has indicated... that this operation should not be used as an excuse or as cover for individuals taking sectarian-motivated retribution," said White House spokesman Josh Earnest. 

The United States ruled out Wednesday any suggestion that talks with Iran over its nuclear program are signs of warming relations between two countries whose diplomatic ties collapsed 35 years ago.

Iran and the so-called P5+1 -- Britain, China, France, Russia, the United States and Germany -- are trying to strike a deal that would prevent Tehran from developing a nuclear bomb, a goal it denies having. In return, Iran is seeking an easing of punishing economic sanctions. 

The US ambassador to South Korea, Mark Lippert, was recovering from surgery Thursday after having his face and arm slashed by a knife-wielding activist in an attack applauded by North Korean state media.

The United States condemned the "act of violence" which saw the ambassador rushed to hospital where his condition was described as stable after two-and-a-half hours of surgery that included 80 stitches to a deep gash on his right cheek.

A homeless man controversially shot dead by police in Los Angeles was from Cameroon, and had stolen the identity of a Frenchman, U.S. and French officials said Wednesday.

The LA Times had initially identified the victim -- killed Sunday in a shooting caught on a video which went viral -- as Charley Robinet, saying he was French, but the French foreign ministry denied this.

The U.S. Senate on Wednesday failed to override a presidential veto blocking a bill that approved construction of the Keystone XL pipeline, halting -- at least for now -- Republican efforts to advance the project.

President Barack Obama issued the veto last month, after the Republican-controlled Congress overcame considerable Democratic opposition to pass legislation approving the controversial pipeline on February 11.