He has pledged $322m (£251m) in new foreign military financing for Ukraine, and confirmed that American diplomats will start gradually returning to the country.

This is the first visit by a senior US official since Russia invaded Ukraine 60 days ago - and Mr Blinken was joined by Defence Secretary Lloyd Austin.

Key developments:

• Ukraine has proposed talks with Russia over the fate of civilians and troops who remain in Mariupol

• No humanitarian routes were established out of Mariupol on Sunday - Ukrainian officials hope to try again on Monday

• Boris Johnson described Vladimir Putin's actions in Ukraine as "nauseating" and "blatant aggression" during a call with UN Secretary-General Antonio Guterres

• An unspecified number of civilians were killed by Russian shelling in Ukraine's Luhansk region on Sunday, local officials claim

• The war in Ukraine is entering its third month with no end in sight - with many thousands of people killed, millions becoming refugees, and cities reduced to rubble

New ambassador unveiled

The media was not allowed to accompany the secretaries on the trip, and their discussions with President Zelenskyy lasted for about 90 minutes.

Details about their talks could not be reported until their delegation was safely out of Ukraine and back in Poland.

The new financing brings the total US security assistance to Ukraine since the invasion began to $3.7bn (£2.9bn).

"It will provide support for capabilities Ukraine needs, especially the fight in the Donbas," an official said.

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A further $400m (£312m) in new foreign military financing will also be shared among 15 other nations in Central and Eastern Europe, as well as the Balkans.

US President Joe Biden will also soon announce his nominee to be ambassador to Ukraine - Bridget Brink, a career foreign service officer.

Mr Zelenskyy had announced that he was going to meet both men during a news conference held in an underground train station in Kyiv on Saturday night.

But the White House had refused to confirm that or discuss details of a possible visit - with US officials later revealing this was a contingency they had planned for.

Embassy staff to gradually return

In other developments, Ukraine's foreign minister has been told that staff from the now-closed US embassy in Kyiv - who have relocated to Poland - are going to begin making day trips to the Ukrainian city of Lviv.

The US State Department has vowed to reopen the embassy there as soon as the situation allows.

"There's no substitute for that face-to-face engagement, and of course there is a symbolism to being back in the country," an official said.

Prior to Mr Blinken's arrival, Ukraine's president had warned that he expected the Americans to produce results.

He had said: "You can't come to us empty-handed today, and we are expecting not just presents or some kind of cakes, we are expecting specific things and specific weapons."

While the West has funnelled military equipment to Ukraine, Mr Zelenskyy has stressed repeatedly that his country needs more heavy weapons, including long-range air defence systems and warplanes.