MOSCOW (AP) — The Latest on the Crimean border dispute between Ukraine and Russia (all times local):

9:55 p.m.

Ambassadors from Russia and Ukraine have traded barbs at a U.N. Security Council meeting over rising tensions between the two countries with both sides expressing concern the situation doesn't spiral out of control.

Following Thursday's meeting, Russian Ambassador Vitaly Churkin said he read the Security Council a statement from his foreign ministry expressing "concern and outrage over this attempt of terrorist sabotage on the territory of the Republic of Crimea."

He added that he hoped the Ukrainians would be prudent enough to avoid a further escalation, but expressed doubt that would happen.

Ukrainian Ambassador Volodymyr Yelchenko, meanwhile, expressed concern about some 40,000 Russian troops he said were amassed near the border, saying "these numbers might reflect some very bad intentions."

He said he hoped the discussion would "help Russia to understand they cannot continue with this kind of behavior."

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5:10 p.m.

A NATO official says the U.S.-led alliance is deeply concerned by rising tensions between Russia and Ukraine and is monitoring the situation closely.

The official, who wasn't authorized to make statements on the record and spoke on condition of anonymity, said Russia had provided no proof of its accusation that Ukraine sent saboteurs to carry out attacks in Crimea.

Ukraine's president has ordered the army to be on combat alert on the country's de-facto border with Crimea and on the front line in eastern Ukraine following Moscow's accusations.

--By John-Thor Dahlburg in Brussels.

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2:50 p.m.

Ukraine's president has ordered the army to be on combat alert on the country's de-facto border with Crimea and on the front line in eastern Ukraine following Moscow's accusations that Ukraine sent in "saboteurs" to carry out attacks in Crimea.

Russia annexed the Black Sea peninsula from Ukraine in March 2014 following a hastily called referendum. The move sparked Russia-backed separatists to begin fighting government forces in eastern Ukraine, where deadly battles are still ongoing.

The Russian intelligence agency FSB on Wednesday said one of its officers and an army soldier were killed over the weekend in two separate incidents while fending off what Moscow described as a series of attacks by Ukrainian "saboteurs."

Ukraine rejected the claims as "fantasy" and "a provocation."

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11:10 a.m.

Russian President Vladimir Putin has held a meeting of the country's top brass to discuss boosting security in Crimea following the reports of foiled terrorist attacks.

The Russian intelligence said Wednesday that two people were killed while fending off what it described as a series of attempted attacks in Crimea by Ukrainian "saboteurs." Ukraine rejected the claims as "fantasy" and "a provocation."

Russia annexed the Black Sea peninsula in March 2014 following a hastily called referendum, an event that sparked Russia-backed separatists to begin fighting in eastern Ukraine, where deadly fighting is still ongoing.

The Kremlin on Thursday said Putin chaired a Security Council session to discuss "additional measures" to ensure security at Crimea's de-facto border, the territorial waters around it and the Crimean airspace.