Hungarian President Pal Schmitt cancelled appointments on his schedule on Friday, a day after being stripped of his doctorate following a months-long plagiarism row which opposition parties say made him unworthy of the job.

The controversy comes at a sensitive time for Hungary as it tries to resolve a lengthy dispute with the European Union on contested new laws to unlock stalled talks on financial support.

Online news portals origo.hu and nol.hu cited unnamed sources in the ruling Fidesz party and its Christian Democrat allies as saying that Schmitt, who took office less than two years ago, could announce his departure later in the day.

He should have done this weeks ago, origo.hu cited a top Christian Democrat politician as saying. The evolution of the situation makes his position more untenable by the hour.

A spokeswoman for the president's office said Schmitt would appear on public television in the evening but declined comment on the reports.

The government spokesman's office declined comment. A Fidesz spokesman was not immediately available for comment.

An earlier statement from the president's office gave no explanation for Friday's cancellations. Schmitt had been due to meet Slovenia's visiting foreign minister and attend an innovation awards ceremony in parliament.

Shortly after the morning announcement, about 20 activists and a lawmaker from the small opposition LMP party staged a protest outside the presidential palace demanding Schmitt's resignation.

Before the ruling, Schmitt was quoted as saying by national MTI news agency he would not resign. Under Hungarian laws, he can be removed by a two-thirds majority vote in parliament.

Schmitt has played an instrumental role in pushing the agenda of his ally, conservative Prime Minister Viktor Orban, signing disputed reforms, such as retroactive taxes, into law.

The decision by Budapest's Semmelweis University to withdraw Schmitt's doctorate is an embarrassment for Orban, who called Schmitt the most suitable candidate for president before his appointment by parliament for a five-year term in 2010.

During his regular Friday morning interview on public radio, Orban deflected questions on whether he thought Schmitt, a former vice president of Orban's ruling Fidesz party and a two-time Olympic gold medal-winning fencer, should resign.

I reiterate, this decision is for him to make on his own, Orban said.

Schmitt, 69, has denied wrongdoing since business news portal hvg.hu broke allegations in January that he had copied large parts of his 1992 thesis from other authors without proper quotes or referencing.

After conducting its own inquiry into the allegations, Semmelweis University stripped Schmitt of his title on Thursday, saying his thesis did not meet scientific and ethical standards.

Last year, two German politicians, including the defence minister, resigned after similar accusations of plagiarism.

The row has marred the 24th anniversary of the foundation of Orban's ruling conservative Fidesz party, which grew from a small opposition youth movement under communism into the most dominant political force in Hungary's post-communist history.

David Dorosz, a member of LMP, said he believed Schmitt had no option but quit.

Pal Schmitt has been in continuous denial since the middle of January, ever since this issue emerged, he told Reuters near a makeshift camp of five tents in LMP's trademark green outside Schmitt's palace in the luxurious castle district.

We are staying until Pal Schmitt resigns, until this case is reassuringly resolved.

(Reporting by Gergely Szakacs and Sandor Peto; Editing by Maria Golovnina, Ron Askew)