Kazakhstan will not accept a single currency in a trade bloc championed by Moscow, a top official said on Wednesday, rejecting a proposal from Russian President Vladimir Putin.

The Russian leader has called for a common currency to be created in the Eurasian Economic Union (EEU), a four-country trade grouping consisting of Armenia, Belarus, Kazakhstan and Russia.

A road accident in Kazakhstan has killed at least 16 people, including three children, Kazakh authorities said Monday, after a minibus collided with a van.

The bodies of 13 of the 19 people travelling in the minibus were found at the crash site in Kazakhstan's southern Jambyl region near Kyrgyzstan Sunday, along with the driver of the van. 

Iranian Foreign Minister Mohammad Javad Zarif on Monday insisted his country wants a "nuclear-free world," days after Tehran's leadership cast doubt on an outline deal to curb its nuclear program. 

Zarif made the comment during a visit to ex-Soviet Kazakhstan as he praised the Central Asian nation for giving up its nuclear weapons after the collapse of the USSR.

Three New York residents accused of offering support to Islamic State jihadists fighting in Syria and Iraq pleaded not guilty to terrorism charges on Friday during a court appearance following their arrest last month.

Uzbekistan nationals Abdurasul Hasanovich Juraboev, 24 and Abror Habibov, 30, together with Kazakhstan citizen Akhror Saidakhmetov, 19, are charged with offering support to a foreign terrorist organization.

Kazakh President Nursultan Nazarbayev on Wednesday set early elections for April 26, a move that will almost certainly see the septuagenarian leader re-elected for another term in the energy-rich state.

"In the interests of the people... and for the sake of the general and strict implementation of the law, I have taken a decision and signed a decree calling early presidential elections for April 26," said the 74-year-old president in a televised address to the nation.

Rakhat Aliyev, an opponent and former son-in-law of Kazakhstan's president, was found dead Tuesday of apparent suicide in an Austrian jail just before he was due to testify in an extortion trial, authorities said.

Aliyev, 52, used strips of gauze bandages to hang himself from a coat hook in the bathroom of his Josefstadt jail cell, which he occupied alone, said Peter Prechtl, head of prison administration. 

Kazakhstan's ruling Nur Otan party on Monday called for early presidential polls in a move that will almost certainly see President Nursultan Nazarbayev re-elected for another five-year term in the former Soviet republic.

The 74-year-old president has one year of his current term remaining. He is unlikely to face any serious opposition in the energy-rich Central Asian country, even though its economy is reeling from low oil prices and the weak Russian ruble.

The foreign ministers of Russia, Ukraine, Germany and France ended their latest Berlin crisis meeting Wednesday with a joint call to cease hostilities in Ukraine but no breakthrough agreement to stop the bloodshed.

The talks had been held against the unpromising backdrop of fresh clashes between Ukrainian government forces and pro-Moscow rebels in the east of the former Soviet republic, and after Ukraine's president accused Moscow of fueling the war with fresh troops and tanks.

Up to four thousand people from Muslim former Soviet Central Asian countries are believed to have joined Islamic State jihadists, a report published on Tuesday said.

Often driven by poverty, some "2,000 to 4,000 have in the past three years turned their back on their secular states to seek a radical alternative," the International Crisis Group said in a briefing on the region.

Kazakh President Nursultan Nazarbayev and Ukrainian counterpart Petro Poroshenko agreed Thursday that the delayed talks on Ukraine conflict with leaders of Russia, France and Germany will take place at the end of the month, Kazakhstan said Thursday.

In a telephone call, the two leaders "noted that the meeting of leaders of Ukraine, Russia, Germany and France in Kazakhstan's capital Astana will happen at the end of January," the Kazakh presidency said in a statement.