Alexis Tsipras sworn in as Greek prime minister

Athens - Alexis Tsipras, the 40-year-old leader of anti-austerity party Syriza, was sworn in on Monday as Greek prime minister, the youngest in 150 years.

Tsipras - wearing a blue jacket and white shirt, characteristically without a tie - also broke with tradition by taking a civil instead of a religious oath, pledging to "always serve the interests of the Greek people".

Tsipras' party took more than 36% of the vote in Sunday's general election, becoming the first elected movement in Europe openly opposed to austerity.

The leftists plan to challenge the multi-billion EU-IMF bailout, which they say has sparked a "humanitarian crisis" in Greece.

Syriza fell two votes short of the required 151-seat majority in parliament, but covered the shortfall through an alliance with nationalist party Independent Greeks (ANEL).

The coalition with ANEL has been described as peculiar, as the two parties are mainly united by their opposition to the EU-IMF bailout but share little common ground beyond that.