BRUSSELS - The EU warned Monday of a continued Russian military build-up in Crimea as it condemned Moscow’s “illegal annexation” of the peninsula from Ukraine one year ago.

Diplomatic chief Federica Mogherini said the 28-nation bloc was also deeply concerned at the deterioration of human rights, demanding free access for outside monitors to investigate the situation.

“The EU reaffirms its deep concern at the continuous military build-up and deterioration of the human rights situation in the Crimean peninsula, including the denial of free speech and the persecution of persons belonging to minorities,” said a statement by Mogherini approved by the EU’s foreign ministers.

The European Union, which has hit Russia with tough economic sanctions over its intervention in Ukraine, “does not recognise and continues to condemn this act of violation of international law,” the statement said.

“The illegal annexation of Crimea and Sevastopol ... is also a direct challenge to international security, with grave implications for the international legal order that protects the unity and sovereignty of all states,” it added. Russia plans celebrations Monday to mark the first anniversary of the annexation which followed a referendum organised by Moscow in a territory long regarded by Russians as a historic slice of their territory. Widely condemned abroad, the annexation boosted Russian President Vladimir Putin’s popularity at home to stellar levels.

Putin described the annexation of Crimea as a mission to rescue the majority Russian-speaking peninsula from Ukrainian “nationalists” who had ousted a Moscow-backed government in Kiev.

In a documentary aired on state TV in Russia on Sunday, Putin also said he was ready to put the country’s nuclear forces on alert as he sought to annex Crimea last year.

Meanwhile, Russian President Vladimir Putin on Monday dismissed days of frenzied “rumours” over his health and whereabouts as he reappeared in public after an unusually long 10-day absence.

The feverish speculation fuelled by social media saw all eyes turn to an otherwise unexceptional meeting planned between Putin and the leader of Kyrgyzstan to see whether the Russian strongman would appear. The typically tardy Putin was two hours late but showed up looking relaxed with no visible signs of ill-health, quelling the rumours that exposed the fragility of Russia’s tightly-controlled political system dominated by one man.

“We would be bored if there were no rumours,” Putin said as he met Kyrgyz President Almazbek Atambayev at the sumptuous Konstantinov’s Palace just outside Saint Petersburg.

In an apparent bid to dispel speculation about his host’s ill health, Atambayev said Putin had taken him for a drive around the palace grounds before their meeting. Dismissing the rumours, a smiling Atambayev said: “In their dreams.”

The usually omnipresent Putin, 62, was last seen in public on March 5 at a news conference with Italian Prime Minister Matteo Renzi.

However the rumour mill went into overdrive when he cancelled a number of scheduled events last week, including a trip to the Central Asian country of Kazakhstan and the planned signing of an alliance agreement with the breakaway region of South Ossetia.

While the Kremlin continued to release footage of Putin in meetings, many speculated that it had been filmed much earlier than when it was broadcast.

The Internet and even traditional media in Europe were set abuzz with speculation Putin had died, been deposed in a palace coup or had once again become a father.

Morbid jokes and gags spread on Russian social networks - one of the last bastions of free speech in Russia - and the hashtag #Putinumer (#Putindead) trended on Twitter.

“Has Putin died?” asked one website where the question was the only thing appearing on a blank page above a button which users could click to check, yielding responses such as “No” and “Still No”.

Putin’s spokesman Dmitry Peskov was forced to fend off countless questions about each rumour, which he dismissed as “March madness.”

He said Putin was busy with Russia’s economic crisis and has “meetings constantly, but not all meetings are public.”

Peskov on Monday said Putin had driven his guest around the palace for about 15 minutes.

“So everyone has now seen the paralysed president captured by generals who has just returned from Switzerland where he was delivering a baby?” he asked sarcastically.

“We no longer want to talk about this. Everything is good.”

Social networks greeted Putin’s appearance with a fresh dose of humour.

“White smoke billows from the Kremlin. Putin still in charge,” Ian Bremmer, a US political scientist, quipped on Twitter.

Independent Internet TV channel Dozhd (Rain) quoted sources as saying the Russian president had been knocked down by the flu and retreated to his residence on Lake Valdai in the north. The Kremlin refused to confirm the report.

Putin’s reappearance comes as Russia marks the one-year anniversary of a referendum in Crimea that led to Russia annexing the Black Sea peninsula from Ukraine and froze Moscow’s ties with the West.

His disappearing act also came amid a febrile political atmosphere in Moscow after the murder of opposition leader Boris Nemtsov, the most shocking assassination of Putin’s 15 years in power.

Some observers suggested that Putin took the time out to deal with increased infighting among political and business elites over Russia’s confrontation with the West and the economic crisis sparked by sanctions and falling oil prices.

One of Russia’s best-loved authors, Boris Akunin, said he was no fan of Putin’s but that he was disgusted to see some people anxiously waiting for a “front-page obituary.”

“I absolutely don’t want the authoritarian regime in Russia to collapse just because Putin disappears of his own accord (or as a result of a palace coup),” he wrote in his blog.

“I want the authoritarian regime to be replaced as a result of people’s conscious choice, their collective actions.”