WRAPUP 11-Mariupol defenders surrender to Russia but their fate is uncertain

(Adds some women aboard buses in Olenivka, Ukrainian and Russian officials on peace talks, Zelenskiy comments)

* Ukrainian soldiers, many wounded, bussed to Russian-held towns

* Mariupol a win for Putin as Russian forces fall back elsewhere

* Russia, Ukraine differ in views on potential prisoner exchange

* Finland, Sweden set to file NATO applications

By Natalia Zinets

MARIUPOL, Ukraine, May 17 (Reuters) - More than 250 Ukrainian fighters surrendered to Russian forces at the Azovstal steelworks in Mariupol after weeks of desperate resistance, bringing an end to the most devastating siege of Russia's war in Ukraine and allowing President Vladimir Putin to claim a rare victory in his faltering campaign.

Even as the Kremlin prepares to take full control of the ruins of Mariupol, it faces the growing prospect of defeat in its bid to conquer all of Ukraine's eastern Donbas because its badly mauled forces lack the manpower for significant advances, some analysts of the Russian campaign said.

Buses left the steelworks late on Monday in a convoy escorted by Russian armoured vehicles. Five arrived in the Russian-held town of Novoazovsk, where Moscow said wounded fighters would be treated.

Seven buses carrying Ukrainian fighters from the Azovstal garrison arrived at a newly reopened prison in the Russian-controlled town of Olenivka near Donetsk, a Reuters witness said.

There were some women aboard at least one of the buses in Olenivka, Reuters video showed. Some of the women wore olive green uniforms, as did most of the men. All of them appeared exhausted. One rested against duffel bags stacked on the floor.

What will happen to the fighters was unclear. The Kremlin said Putin had personally guaranteed the prisoners would be treated according to international standards, and Ukrainian officials said they could be exchanged for Russian captives.

TASS news agency said a Russian committee planned to question the soldiers, many of them members of the Azov Battalion, as part of an investigation into what Moscow calls "Ukrainian regime crimes".

The denouement of a battle which came to symbolise Ukrainian resistance gives Moscow total control of the Azov Sea coast and an unbroken stretch of eastern and southern Ukraine, even as its troops retreat from the outskirts of Kharkiv in the northeast.

Officials from both sides said on Tuesday that peace talks aimed at ending the war had stagnated. Negotiators last convened in-person in late March, and there has been little communication between them in recent weeks.

Russia's Deputy Foreign Minister Andrey Rudenko said Ukraine "has practically withdrawn from the negotiation process," While Russian negotiator Leonid Slutsky said talks were not being conducted in any format.