Berlin: German Chancellor Angela Merkel said she has no regrets about her 2015 decision to open the country's borders to hundreds of thousands of refugees and added she will not be deterred from campaigning by angry hecklers.

In an interview with the Welt am Sonntag newspaper on Sunday, Merkel denied she had made any mistakes with her open-door policy even though the arrival of a million refugees over the last two years from Syria and Iraq opened deep rifts in her conservative party and depressed its support.

Four weeks before the Sept. 24 election, an Emnid opinion poll on Sunday showed Merkel's conservatives would win 38 percent, or 15 points ahead of the centre-left Social Democrats (SPD). That is up from 32 percent in February but well below the 41.5 percent her party won in the last election in 2013.

"I'd make all the important decisions of 2015 the same way again," Merkel said. "It was an extraordinary situation and I made my decision based on what I thought was right from a political and humanitarian standpoint.

"Those kinds of extraordinary situations happen every once in a while in a country's history," she added. "The head of government has to act and I did."

Her decision to open the borders contributed to a surge in support for the far-right Alternative for Germany (AfD) party, which pollsters say could win up to 10 percent in the September election.

Merkel, seeing a fourth term, has had to contend with loud and sustained heckling from demonstrators strongly opposed to her refugee policies so far on the campaign trail.

The volume and intensity of the protests have been especially strong in her home region in formerly communist eastern Germany. But the 63-year-chancellor said she would not be kept away from areas where animosity towards her runs high.

"We're a democracy and everyone can freely express themselves in public the way they want," she said. "It's important that we don't go out of our way to avoid certain areas only because there are a bunch of people screaming."

Support for Merkel and her party has recovered somewhat after the influx of refugees slowed in 2016 to 280,000 and fell even further to about 106,000 in the first seven months of this year.

Merkel said it was unfair that Greece and Italy were left on their own carrying the full burden of the refugee crisis "simply because of their geography". She added she would not stop pushing for the fair distribution of refugees across the European Union.

"That some countries refuse to accept any refugees is not on. That contradicts the spirit of Europe. We'll overcome that. It will take time and patience but we will succeed."