By Mirjam Donath
UNITED NATIONS, March 19 (Reuters) - A United Nations human rights monitoring team arriving this week in Ukraine hopes to travel quickly to Crimea, where concerns have been raised over treatment of opposition activists and ethnic minorities, a top senior U.S. human rights official said on Wednesday.
The Crimean region, newly annexed by Russia, urgently needs independent monitors to report on human rights violations, Ivan Simonovic, the U.N. assistant secretary-general for human rights, told the United Nations Security Council.
"I have serious concerns about the situation in Crimea, where the situation remains tense with respect to protection of human rights," he said. "I'm deeply concerned about the human rights of those who oppose recent political events in Crimea."
Russia's annexation of Crimea has left the United States and Europe groping for ways to increase pressure on a defiant Russian President Vladimir Putin, who has moved to annex Crimea into Russia following a Kremlin-backed referendum there.
On Wednesday, Russian troops stormed Ukraine's naval headquarters in the Crimean port of Sevastopol and raised their flag.
At the United Nations, Simonovic said he was newly returned from Ukraine but had been unable to visit Crimea as authorities there initially would not receive the mission nor ensure its security.
However, he said he has now received an invitation to visit the Crimean capital of Simferopol, but did not elaborate on who extended the invitation.
He said he hoped a similar visit to Crimea by members of the human rights monitoring team would take place soon.
Simonovic has said he was particularly concerned about the region's ethnic minority Tatars. The Tatars, Sunni Muslims of Turkic origin, make up 12 percent of Crimea's population of 2 million people.
He said on Wednesday there were credible reports that a local Crimean Tatar activist was found dead and evidence showed he had been mistreated.
Vitaly Churkin, the Russian ambassador to the U.N., told the Security Council that Simonovic's report on human rights was "one-sided."
"The Crimean authorities have guaranteed the rights of all minorities, without any exceptions," he said.
U.S. Ambassador Samantha Power told the Security Council, "If there was ever a time to be concerned about human rights in Crimea, it is now."
Crimean Tatars are rightfully fearful of deportation and discrimination, she said.
"In addition, we are seriously concerned about activists, civil society leaders, media restrictions and journalists in Crimea," she said.
Crimea's pro-Russian authorities have held out the promise of guaranteed Tatar representation in the local government, proper land ownership rights - something many Tatars lack - and financial aid. They have also pledged to extend gas supplies to remote Tatar areas.
Russia and pro-Russian Crimean authorities have accused the opposition and new government of abuses, including threats and harassment of ethnic Russians and Russian speakers in eastern Ukraine.
The new Kiev government said the former prime minister, Viktor Yanukovich, was guilty of rights abuses and murder for ordering a crackdown on protesters that left dozens dead.
Simonovic said the head of the monitoring mission arrived in Ukraine last week and that a team of nearly three dozen international and Ukrainian staff by Friday will be in place in Kharkiv and Donetsk in eastern Ukraine.
The human rights monitoring mission was requested by Ukraine's new government and will be operational for three months, Simonovic said last week.
United Nations chief Ban Ki-moon meets Putin in Moscow on Thursday and travels to Kiev on Friday to urge a peaceful end to the crisis. (Editing by Ellen Wulfhorst and Leslie Adler)