Hungary's foreign minister, Peter Szijjarto, will travel to Moscow on Wednesday to meet his Russian counterpart Sergei Lavrov, his office told AFP.

"They will discuss bilateral issues and exchange views on the latest international developments," the foreign ministry said in an email.

Tens of thousands of protesters rallied in Budapest and other Hungarian cities Monday in a show of "indignation" over the policies of Prime Minister Viktor Orban's right-wing government.

The "Day of Indignation" was the latest in a series of large street protests begun last month after Orban's right-wing Fidesz party proposed a tax on Internet usage.

Hungary's Prime Minister Viktor Orban on Friday dismissed corruption claims cited by Washington as the reason for U.S. entry bans on six senior Hungarian officials in October that have soured already frayed bilateral relations.

"This is just a scrap of paper," Orban on Friday morning in an interview with state radio, referring to a document published by the government on Thursday said to come from the U.S. embassy in Budapest.

The United States is putting Hungary under "great pressure" over its energy ties to Russia because of the Ukraine crisis, Prime Minister Viktor Orban was quoted as saying for the first time Friday.

"The U.S. is putting Hungary under great pressure," Hungarian media cited Orban as saying in Munich, Germany late Thursday after a meeting with Bavarian state premier Horst Seehofer.

A 16-year-old Dutch girl allegedly on her way to Syria has been intercepted by Hungarian police, authorities said Wednesday, in the latest case of a European teenager trying to join jihadists.

The girl was on a train from the Hungarian capital Budapest to Belgrade in Serbia on October 29 when police stopped her because she had forged documents, Hungary's Counter-Terrorism Center (TEK) said.

The top U.S. diplomat in Hungary was under fire Tuesday after attending an anti-government protest, with Prime Minister Viktor Orban's government accusing him of interference amid a  worsening of relations.

Washington's charge d'affaires, Andre Goodfriend, was photographed by local media among tens of thousands of protestors in Budapest on Sunday demanding Orban scrap a planned Internet tax.

The Hungarian consulate in Istanbul on Monday became the sixth diplomatic mission in Turkey's largest city to receive a suspicious powder through the post but the authorities said there was no indication the substance was dangerous.

The consulates of Belgium, Canada, Germany, France and the United States -- all countries involved in the international coalition against Islamic State (IS) jihadists -- had reported receiving the yellow powder on Friday.

The top U.S. diplomat in Hungary warned Friday "negative trends" have taken hold in the EU member, days after Washington issued entry bans on six government officials it suspects of corruption.

"All the reports are showing negative trends, we want to stop these trends as we are good allies," U.S. charge d'affaires Andre Goodfriend told a news conference in Budapest on Friday. "You can see the line going downward".

Hundreds of Hungarians took part in a "Roma Pride" march in Budapest Sunday to celebrate the country's largest ethnic minority, a community scarred by widespread prejudice.

Around 500 people walked through the city center chanting "Opre Roma!" (Up Roma!) and holding placards of famous figures of ethnic-Roma background like British actor Charlie Chaplin and Spanish footballer Jesus Navas.

Hungary on Monday banned a conference of the U.S.-based white supremacist National Policy Institute (NPI) set for this weekend, calling the organization "racist."

Interior Minister Sandor Pinter has concluded that the speakers invited to the event "are proponents of racist ideologies" and that allowing them to speak would contravene Hungary's constitution, the ministry said in a statement.