Spains king on Thursday urged an end to the graft scandals that have long plagued his nation, as he opened a new session of parliament after nearly a year of political paralysis.

The matter is particularly close to heart for Felipe VI, whose sister is on trial over the alleged illegal business dealings of her husband -- the verdict of which is expected by year-end.

At the same time, ex-lawmakers and politicians from the ruling conservative Popular Party (PP) are on trial in one of Spain's biggest graft scandals -- the so-called Gurtel affair -- involving alleged kickbacks, fake invoices and Swiss bank accounts.

"Corruption... must become but a sad memory of a scourge that we have to defeat," Felipe VI said in a speech that was given a standing ovation, except from lawmakers belonging to far-left, anti-monarchy party Podemos, many of whom stayed seated.

The parliamentary opening comes just weeks after conservative Prime Minister Mariano Rajoy took power again following 10 months of political limbo.

The period was marked by two elections that produced no clear winner as upstart centrists Ciudadanos and far-left Podemos upset the traditional two-party system.

Rajoy's comeback was only made possible after the Socialist party decided to abstain in a crunch parliamentary confidence vote in October, instead of voting against him.

But unlike in 2011 when he came to power with an absolute majority, the PP only has 137 out of 350 MPs, meaning Rajoy will have to negotiate every bill with the opposition.

Among the opposition are 71 lawmakers from a coalition made up of Podemos and smaller, former communist party Izquierda Unida, many of whom are anti-monarchy and showed it Thursday.

Several lawmakers stayed seated during the national anthem, and subsequently refused to greet the king, Queen Letizia and their daughters Leonor, 11, and Sofia, 9 -- as is customary.

Union leader and lawmaker Diego Canamero also wore a black sweatshirt to parliament with the statement "I didn't vote for any king."

"Letizia, if you're going to take your daughters to the chamber, be prepared for a campaign of unlimited insults," she said.

Bescansa was referring to her own experience of bringing her baby boy to parliament in January, when it opened albeit without a fully-functioning government -- a move for which she was strongly criticised.