Russia's investigators on Thursday said its probe into the 2010 crash of Polish presidential jet is almost complete, rejecting claims that Russian air traffic controllers were to blame.

"The Russian investigation sees no grounds to talk of even minimal responsibility of the flight control group for the air crash," a statement by the Investigative Committee said.

Ukrainian pro-Russian separatist leader Alexander Zakharchenko accused the Kiev government of "totally ignoring" the terms of a peace deal and warned in an interview with AFP that fighting might resume.

The warning came as international monitors overseeing a fragile February truce -- which is largely holding despite isolated clashes -- reported "an increase in the number of ceasefire violations in the Donetsk region" where Zakharchenko's forces are in control.

Talks between the Syrian government and members of the tolerated opposition were set to end Thursday in Moscow with little sign of progress towards ending the spiraling conflict in the country.

Russian Foreign Minister Sergei Lavrov was due to open a final meeting between the two sides but opposition activists said there was little chance of a breakthrough after holding two days of talks with the delegation of Bashar Assad's regime.

The White House said Wednesday it would not name those behind a cyber attack on official Washington targets last October, after reports blamed Russia.

"Our investigators have concluded that it's not in our best interest to identify the entity that may be responsible for this specific activity of concern," White House spokesman Josh Earnest said.

Estonia's pro-NATO Prime Minister Taavi Roivas on Wednesday completed formation of a ruling coalition after a March re-election overshadowed by tensions with neighboring Russia.

Roivas's center-right Reform party renewed its partnership with leftist Social Democrats and roped-in the conservative IRL party to command 59 seats in the 101-member parliament, the Baltic New Service (BNS) reported Wednesday.

Two soldiers and a pro-Russian rebel were killed in the last 24 hours in eastern Ukraine where isolated clashes continue in breach of a truce to end the yearlong war, officials on both sides said Wednesday.

Two army troops died and four were injured, army spokesman Andriy Lysenko said without giving any details. He also accused separatist rebels of violating a February ceasefire a dozen times during the same period, saying rebels used heavy weapons including mortars.

Another Armenian soldier was killed this week as clashes intensified between arch-foes Azerbaijan and Armenia, locked in a decades-long dispute over Nagorny Karabakh region, Armenian officials said on Wednesday.

"On April 7 (Tuesday), a soldier was shot dead on the Karabakh frontline by an Azerbaijani sniper," the separatist region's defence ministry said in a statement.

One of the suspects in the murder of Alexander Litvinenko claimed Wednesday that the ex-spy accidentally poisoned himself as he laid out his defense before giving testimony to a British inquiry.

Businessman Dmitry Kovtun and a second Russian, former Kremlin bodyguard Andrei Lugovoi, are wanted by British police for allegedly poisoning Litvinenko in a London hotel using tea laced with polonium-210, a radioactive isotope.

Gulf countries are making a push for U.N. sanctions to be imposed on the leader of Yemen's Huthi rebels and the ex-president's son, according to a draft resolution that could come up for a vote this week.

Jordan circulated the draft resolution prepared by Gulf states to the Security Council late Monday as Russia stepped up its criticism of the Saudi-led air campaign in Yemen.

A Russian nuclear submarine undergoing repairs caught fire Tuesday, officials said, although reports indicated the vessel was not carrying nuclear fuel.

"There was a fire" on the submarine at the Zvyozdochka shipyard in the northern city of Severodvinsk, according to a representative who answered the phone at the local emergency services center.