Mariano Rajoy was struggling to hold Spain's fragile government together as he faced calls for snap elections and the potential loss of a key coalition partner after he was accused of triggering "social alarm" over a corruption scandal.

Rocked by Thursday's conviction of his Popular Party's (PP) former treasurer for money laundering, Mr Rajoy was told by the opposition that it would be tabling a no-confidence motion in the prime minister.

Meanwhile, Ciudadanos, the liberal party whose backing is crucial to the conservative PP in Spain’s hung parliament, issued Mr Rajoy with an ultimatum to call a snap general election or face a separate motion forcing him to do so.

Spain was plunged into crisis a day after Luis Bárcenas, the PP's former treasurer, was finally convicted alongside other senior members of the PP for offences including falsifying accounts, influence-peddling and tax crimes. They were sentenced to a combined 351 years behind bars.

The case, which relates to the use of a slush fund by the Conservatives in the 1990s and early 2000s to illegally finance campaigns, has plagued Mr Rajoy since he came to power in 2011. He has always denied wrongdoing.