The German government told the Croatian news agency Hina that Merkel “lacks time” to come to Zagreb.

However, the Croatian media have interpreted Merkel’s cancellation as a message of dissatisfaction with Croatia’s reluctance to extradite Josip Perkovic, a former Croatian secret service official suspected of murdering a Croat in Germany in 1983.

The same day Merkel cancelled her trip to Zagreb, Germany’s countercriminal office renewed its arrest warrant for Perkovic, originally filed several years ago.

After Croatian media recently reported that Germany intends to use European Arrest Warrant mechanism to request the extradition of Perkovic to Germany after Croatia joins the EU, Croatia announced it will change the law, restricting use of the European Arrest Warrant mechanism to crimes perpetrated after August 2002.

Despite Croatian government officials and President Ivo Josipovic claiming the change has nothing to do with Perkovic, the move was widely interpreted as an attempt to avoid extraditing Perkovic.

European Commission spokesperson Mina Andreeva on Wednesday said that Croatia “would have to implement the European Arrest Warrant mechanism even on cases before its EU accession”.

But Croatian authorities also said there is no possibility of extraditing Perkovic to Germany, because the Croatian judiciary have investigated the case and found no evidence to charge Perkovic.

The authorities add that the the case fell under statute of limitations back in 1998.

Perkovic, who is retired and lives in Croatia, was a senior official in the Communist Yugoslav secret service SDS, and one of the key figures in the secret services in independent Croatia.

The German courts charge him with organising the murder of Josip Djurekovic, a former general director of the Croatian oil firm Ina, who emigrated from Yugoslavia to Germany and was killed July 28 1983 in Wolfratshausen near Muenchen.

Krunoslav Prates, a Croat living in Germany, was sentenced to life in Germany 2008 for the crime.

At the time Yugoslavia dissolved, the new Croatian authorities under Franjo Tudjman, himself a former Communist, asked Perkovic to organise the Croatian secret service, which he did.

He was assistant defence minister and assistant to Miroslav Tudjman, Franjo Tudjman’s son and the formal leader of Croatian secret service, HIS.