Q&A: Rajoy party scandal in Spain
Allegations of illegal party funding are swirling around Spain's Prime Minister Mariano Rajoy. The opposition Socialist Party has called for him to resign and there is pressure for him to give a full explanation.
What are the allegations?
The central claim is that documents published by El Pais newspaper in January are a list of illegal payments linked to senior members of the ruling Popular Party (PP).
After initial denials, the party's former treasurer, Luis Barcenas, admitted that he wrote the documents, which appear to involve undeclared or secret cash payments.
He says he made numerous bonus payments - in cash - to Mr Rajoy and other senior party members, from a fund of donations from businesses.
Mr Rajoy and other PP members deny receiving illegal payments and accuse Mr Barcenas of trying to blackmail them.
Mr Barcenas is in custody, accused of corruption and tax fraud. He denies wrongdoing.
In another twist, El Mundo newspaper published friendly text messages sent to Mr Barcenas by Mr Rajoy.
One message, dated 18 January - after the slush fund allegations first broke - says "Luis, I understand. Stay strong. I'll call you tomorrow. A hug."
What do the documents say?
The handwritten documents, marked with dates from 1990 to 2008, contain a series of columns. The names of senior PP members often appear in a left-hand column. In another column, marked as "have" or "out", appear numbers.
Private companies and businessmen are also mentioned in the documents. Alongside these names, in another column marked "owed" or "in", there are also often large numbers.
El Pais says these numbers were "donations", and that 70% of them would not have fallen within Spain's party financing laws at the time.
The law stated that a private donor could not give more than 60,000 euros (£52,000; $78,000) to a political party in a single year, and the money could not come from a company carrying out work commissioned by the Spanish state.
El Pais describes the documents as the PP's "hidden accounts".
El Mundo says original ledger entries it published in July have demolished PP denials about their authenticity.
The PP's position has been that it "it does not know of the notes nor their content, and it does not in any way recognise them as the accounts of this political organisation".
What do the documents NOT say?
If the documents are genuine, they still do not prove that all the people or companies mentioned actually received or made any of the alleged payments.
It is also possible that payments made might have been declared.
Who is Luis Barcenas?
Luis Barcenas is a former senator, and was the treasurer of the Popular Party from 1990 to 2009.
He stepped down from the post, after being implicated in a separate, high-profile corruption case in Spain, known as the Gurtel scandal.
In that case, he stands accused of tax fraud and receiving illegal payments.
As part of an ongoing investigation into the Gurtel case, it has emerged that Mr Barcenas stashed up to 48m euros in Swiss bank accounts. Prosecutors allege that some of the funds stem from illegal party donations or kickbacks from businesses seeking contracts.
The PP has denied that the account is in any way linked to the party.
He was placed in custody in June ahead of a trial for tax evasion.
What does Spain's prime minister have to say?
Mr Rajoy has told parliament he made a mistake in trusting Mr Barcenas.
"I made a mistake in maintaining confidence in someone who we now know did not deserve it," he told MPs at a special sitting, where he offered to give "the necessary clarifications" about the scandal.
Mr Rajoy's name is written a number of times in the documents published by El Pais.
Alongside his name are numbers totalling 25,200 for each year, from 1999 to 2008, the dates to which the documents apparently correspond.
The prime minister has publicly denied ever having received any secret payments and has refused to resign.
How damaging could this case be?
People in Spain are used to corruption cases against politicians being reported in the media, and sometimes going to court.
However this is the first time that so many current and former leaders of the governing party, including the prime minister, have been linked to such a high-profile case.
Even journalists in Spain's right-wing newspapers who back the PP believe the scandal has already damaged the image of the prime minister and his party.
There have been relatively small, but angry, protests outside the party's headquarters in Madrid since the El Pais revelations in January.
EU leaders and officials have been unusually tight-mouthed over the scandal, given the importance of Spain to the eurozone, BBC Europe editor Gavin Hewitt reports.
German Chancellor Angela Merkel and others have placed a lot of faith in Mr Rajoy, who is regarded as a safe pair of hands for painful reforms aimed at reviving Spain's economy.
What happens next?
The PP has announced an internal audit of its finances and Mr Rajoy has said he will publish his earnings online.
Spain's chief state prosecutor has said there could be enough evidence to investigate the allegations against the PP, to see if anything illegal has taken place.
The PP's deputy leader, Maria Dolores de Cospedal, has been summoned to appear before an investigating judge on 14 August.
While the Socialist opposition has called for the prime minister to resign, as things stand that looks unlikely, given Mr Rajoy's comfortable majority in parliament.
However, our Europe editor says it would be interesting to know whether he would agree to an independent judicial enquiry to establish the truth of the allegations.