Kerry and Lavrov hold Geneva discussions

US Secretary of State John Kerry is meeting his Russian counterpart for the first time since he accused Russia of lying about its role in Ukraine's war.

The talks with Sergei Lavrov in Geneva coincide with a UN report on human rights violations and the humanitarian crisis in east Ukraine.

The UN says the conflict has claimed at least 6,000 lives, with hundreds killed in the past few weeks alone.

A fragile ceasefire is holding despite some fighting in recent days.

At his meeting in Geneva, Mr Kerry is also expected to raise the brutal murder of a Russian opposition politician in Moscow on Friday.

Boris Nemtsov, who was shot on a bridge near the Kremlin, had been planning an anti-war rally and was said to be working on a report to expose the presence of Russian troops in Ukraine.

His allies accused the Kremlin of involvement but Russian President Vladimir Putin condemned the murder as "vile" and vowed to find the killers.

Mr Kerry will press for an investigation that he said should examine not only who pulled the trigger, but who ordered, funded and co-ordinated Mr Nemtsov's murder.

Separately, the US secretary of state is also expected to renew negotiations with Iran's Foreign Minister, Mohammad Javad Zarif, on Tehran's nuclear programme.

There is an end of March deadline to reach agreement on limiting the programme, in return for an easing of economic sanctions on Iran.