Leaving concerns over the implications of the mounting debt crisis behind them, Europeans welcomed 2012 in style.

Big crowds gathered in almost all major cities in the continent to celebrate the arrival of 2012. In London, tens of thousands of revellers witnessed the events, especially fireworks over the Thames. Moscow's Red Square, Berlin's Brandenburg Gate, Spain's Madrid city all witnessed huge crowds.

But Europe's leaders urged the people to remain cautious in view of the debt crisis, in their New Year greetings. The somber tone was evident in the message of German Chancellor Angela Merkel who warned that 2012 would be tougher than 2011.

French President Nicolas Sarkozy too shared the same view. "What is happening in the world announces that 2012 will be a year full of risks but also full of possibilities. We have to be courageous and we have to be lucid," Sarkozy said in a televised message to the nation. Greek Prime Minister Lucas Papademos too warned of a difficult year.

Here are some of the moments of New Year celebrations across Europe: