The talks between Merkel and Karzai are expected to focus on the reconstruction of Afghanistan, the ongoing fight against the Islamist Taliban and the increasingly dangerous situation faced by German troops in northern Afghanistan.

German news magazine Der Spiegel reported in its latest edition that the Taliban was planning massive attacks on German soldiers to put pressure on politicians as the September general election draws close.

Germany has 3,800 soldiers based in the relatively tranquil north of the country while US, British and Canadian troops are battling the Taliban in the south.

A German soldier was killed two weeks ago in a Taliban ambush near the city of Kunduz, the 32nd German soldier killed while serving with the NATO-led International Security and Assistance Force (ISAF) in Afghanistan.

Karzai must do more to put his house in order.

Meanwhile, in an interview with German newspaper Berliner Zeitung, the EU's foreign affairs commissioner, Benita Ferrero-Waldner, raised the pressure on Karzai to do more to put his troubled country's affairs in order.

On Saturday Ferrero-Waldner urged Karzai to do more to fight corruption and put his country on the path to modernization.

The Afghan government must show, better than they have in the past, “that they are working to move the country forward; that they are working to develop an administrative infrastructure, and to crack down on corruption,” Ferrero-Waldner told the paper. “Mistakes were made in the past,” she added.

German foreign policy expert Eckhart von Klaeden, of Merkel's Christian Democratic Party, told the Berliner Zeitung Karzai needed to act "more decisively against corruption and the cultivation of drugs." There were signs "that this decisiveness is lacking," he said.

Green Party defence spokeswoman Winfried Nachtwei warned the German government against complacency.

Merkel should say "what Germany will do against the downward spiral which we are witnessing in Afghanistan's security and political legitimacy," Nachtwei said.

Both Karzai and Merkel are seeking re-election this year in their respective countries. Merkel has to deal with growing voter antipathy towards Germany's involvement in Afghanistan.