BERLIN (BLOOMBERG) - Germany's election front-runner apologised after video images captured him laughing while the country's president was promising aid to victims of floods that have killed at least 130 people.

It is a potential embarrassment for Armin Laschet, who heads Chancellor Angela Merkel's governing conservative party and is its candidate to succeed her in the Sept 26 election.

He said he regretted "the impression created by a conversational situation."

Laschet was caught on video standing with a group of officials some distance behind German President Frank-Walter Steinmeier while they were visiting Erftstadt, a town devastated by floods this week.

While Steinmeier appeared to search for words to express sorrow and promise aid, Laschet chatted with his own delegation and at one point burst into laughter.

"This was inappropriate and I am sorry," Laschet said on Twitter after political rivals and social-media commenters criticised him.

Laschet, a Christian Democrat, was on home turf in North Rhine-Westphalia, a state that has the second-highest regional death toll from the floods.

While Merkel's Christian Democratic-led party bloc is leading the opposition Green party in the polls, Laschet is likely to need support from a coalition partner to govern with a parliamentary majority even if his bloc wins the most votes in September.