Berlin  - German Chancellor Angela Merkel and US president-elect Barack Obama agreed in a telephone call to work together to help solve global challenges, a Berlin government spokesman said Friday.

The stabilization of Afghanistan, the global financial crisis, climate change and Iran's controversial nuclear programme require closer cooperation, the spokesman said in a statement following Thursday evening's telephone call.

Merkel also congratulated Obama on his "historic" election victory, the statement said.

The president-elect thanked Germany for the warm welcome he received in Berlin when he addressed a crowd of around 200,000 in July. Obama had also met with Merkel during his Berlin visit.

Obama telephoned various foreign leaders after his November 4 election victory.

Merkel and Obama are expected to meet when the chancellor travels to Washington on November 14 for the world financial summit.

Once in office, Obama is expected to press Germany to increase its involvement in Afghanistan by sending troops to the volatile south of the country. Merkel said later on Friday that she would not change Germany's role in Afghanistan despite the new administration. (dpa)