* Moscow says southern Ukraine is also in focus now

* U.S. says any annexations would not go unchallenged

* Europe braces for restart of Nord Stream gas link

* US estimates 15,000

July 21 (Reuters) - Ukrainian armed forces said on Thursday they had killed 111 Russian soldiers in the south and east over the past day, as comments from Russia's foreign minister showed the Kremlin's goals had grown during the five-month war.

Foreign Minister Sergei Lavrov told state news agency RIA Novosti on Wednesday that Russia's military "tasks" in Ukraine now go beyond the eastern Donbas region.

Lavrov also said Moscow's objectives will expand further if the West keeps supplying Kyiv with long-range weapons such as the U.S.-made High Mobility Artillery Rocket Systems (HIMARS).

"That means the geographical tasks will extend still further from the current line," he said.

The Russian-installed administration in the partially occupied Ukrainian region of Zaporizhzhia said Ukraine had conducted a drone strike on a nuclear power station there, but the reactor was not damaged.

Reuters could not independently verify the report. Ukrainian officials had no immediate comment.

The Ukrainian military reported heavy and sometimes fatal Russian shelling amid what they said were largely failed attempts by Russian ground forces to advance.

In the previous 24 hours, Ukrainian forces said they had destroyed 17 vehicles, some of them armoured, as well as killing more than 100 Russian soldiers.

In a Facebook post, the forces said they saw no signs the Russians were creating special strike groups to push a new offensive.

Reuters could not independently verify the battlefield accounts.

US OPPOSES ANNEXATIONS

Russia's invasion has killed thousands, displaced millions and flattened cities, particularly in Russian-speaking areas in the east and southeast of Ukraine. It has also raised global energy and food prices and increased fears of famine in poorer countries as Ukraine and Russia are both major grain producers.

The United States estimates that Russian casualties in Ukraine so far have reached around 15,000 killed and perhaps 45,000 wounded, CIA Director William Burns said on Wednesday.

Russia classifies military deaths as state secrets even in times of peace and has not updated its official casualty figures frequently during the war.

The United States, which had said on Tuesday that it saw signs Russia was preparing to formally annex territory it has seized in Ukraine, promised that it would oppose annexation.

"Again, we've been clear that annexation by force would be a gross violation of the UN Charter, and we would not allow it to go unchallenged. We would not allow it to go unpunished," State Department spokesperson Ned Price said at a regular daily briefing on Wednesday.