BERLIN, March 19 (Xinhua) -- German Chancellor Angela Merkel on Monday congratulated to Russian President Vladimir Putin's re-election, calling for addressing key challenges in bilateral and international relations.

"Today, it is more important than ever to continue the dialogue with one another and to foster relations between our states and peoples," said Merkel, according to a statement by the Chancellery.

"On this basis, we should strive to constructively address key bilateral and international challenges and find viable solutions. I wish you success in the tasks ahead of you," said Merkel.

Ties between the two countries have soured after the Ukraine crisis in 2014, and have been further undermined in recent days as Germany joined the Western bloc in accusing Russia's alleged nerve agent attack in Salisbury, Britain, which was denied by Moscow.

German government spokesperson Steffen Seibert said on Monday noon that Germany had different opinions with Russia and it criticizes Russia's policies on issues ranging from Russian politics to the conflicts in Ukraine and Syria.

However, Seibert added that it was important to maintain contacts with the Russian leadership.

In another development, German President Frank-Walter Steinmeier congratulated Putin on his victory in a statement Monday, urging the Russian President to use the occasion of his re-election to push for a normalization of relations with Germany and Western Europe.

Putin was elected president for the fourth time in a landslide victory on Sunday, gaining "unprecedented" public support throughout his campaigns.

Putin won 76.6 percent of ballots after 99.83 percent of votes have been counted in Sunday's presidential election, the Central Election Commission (CEC) Chair Ella Pamfilova said, citing preliminary data.

In accordance with the law, a candidate garnering more than half of the votes goes to the Kremlin. Putin got 52.9 percent of votes in 2000, 71.3 percent in 2004 and 63.6 percent in 2012.