More than 1,000 people protested outside the governing Popular Party (PP) headquarters in the capital.

There is widespread anger over allegations of illegal cash payments to members of the conservative PP.

Prime Minister Mariano Rajoy is under pressure to give an explanation to parliament. He denies wrongdoing.

The demonstrations on Thursday night caused disruption to traffic in central Madrid.

Protesters held placards calling on the government to resign. There was also a protest outside the PP offices in Valencia.

The corruption allegations coincide with Spain's worst economic crisis for decades, with record unemployment and many Spaniards struggling to make ends meet.

The PP's former treasurer, Luis Barcenas, is in custody facing trial for corruption and tax fraud. He denies the allegations.

He says he made numerous bonus payments - in cash - to Mr Rajoy and other senior party members, out of the party slush fund of illegal donations by businesses.

Ledgers detailing such payments, and apparently written by Mr Barcenas, have been published in two Spanish newspapers - El Pais and El Mundo.

Mr Rajoy and other PP members have repeatedly denied that they received illegal payments.

The prime minister has accused Mr Barcenas of blackmail.

For now at least there is no sign that Mr Rajoy might resign over the scandal, the BBC's Tom Burridge reports from Madrid. The PP has a comfortable majority in parliament.