By Philip Pullella

MIERCUREA-CIUC, Romania - Tens of thousands of people gathered on muddy slopes in Transylvania on Saturday to see Pope Francis visit one of Romania’s most popular Catholic shrines as bad weather disrupted his second day in the country.

Pope Francis was to have flown by plane from Bucharest to the city of Bacau and then by helicopter to the Sumuleu-Ciuc shrine in this town nestled in the mountains, where local officials estimated the crowd at more than 80,000.

But thunderstorms, low clouds and rain forced him to fly to the city of Targu Mures, on the other side of the Carpathian mountains, and be driven for more than two hours along winding roads to the site.

From there Francis was due to continue by helicopter to the city of Iasi to visit Catholics in the remote region of Moldova, close to the border with the former Soviet Union’s satellite Republic of Moldova.

But Vatican officials said he would drive back to Targu Mures and fly by plane to Iasi before returning to Bucharest.

Transylvania, which was part of the Austro-Hungarian Empire until the end of the First World War, has a large ethnic Hungarian population and there have been tensions sometimes between ethnic Hungarians and Romanians.

Ethnic Hungarians, many of whom are Catholic in a predominantly Orthodox Christian nation, are the largest minority in Romania.

This has often caused friction between the two European Union neighbors with tensions flaring occasionally over the public use of ethnic minority flags.

Hungarian Prime Minister Viktor Orban has visited Transylvania many times privately to meet local Hungarian leaders and outline his policy views.

In 2015, Romania rebuked him for posting on his Facebook page symbols it said suggested Budapest favors autonomy for Romanian territory populated mainly by ethnic Hungarians, calling such “revisionism” unacceptable.

The Vatican said Hungarian President Janos Ader attended the Mass at the Sumuleu-Ciuc shrine, the Vatican said.