Discounting objections from human rights activists related to a December riot in Kazakhstan, Germany had forged on Wednesday a rare earths and technology agreement swap with the Central Asian nation, where the European giant gains access to the latter's abundant rare earths and other raw minerals in exchange for technological advancement and investment.

The strategic partnership is worth nearly $4 billion or 3 billion euros contained in 50 separate accords, including an agreement between Kazakhstan's state railway company and Siemens that will pave for the renovation and upgrade of the former Soviet state's rail network. Small other deals involving German industrial gases group Linde, chemicals group Lanxess and steel firm ThyssenKrupp were also included in the list, Reuters reported.

The heads of the two countries, German Chancellor Angela Merkel and Kazakhstan President Nursultan Nazarbayev, came up with the agreement after the latter's two-day official visit to Berlin.

However, not all were delighted with the milestone agreement as human rights activists criticized Ms Merkel's apparent cold, uninterested take on the December riot between police and protesters in a western Kazakh oil town that left more than a dozen people dead.

But Ms Merkel said she had raised the issue of human rights and was able to persuade the 71-year-old Kazakh president to investigate the December riot, adding Mr Nazarbayev will be calling for a commission of inquiry to find out what really happened before and during the clash.

"German foreign policy is always value-based, and so when discussing economic interests we also talk about human rights, the adherence to democratic principles," Ms Merkel said during a joint news conference in Berlin.

Human Rights Watch group condemned the arrangement of the two countries, particularly noting that the human rights situation in Kazakhstan had seriously deteriorated, the Financial Times reported.

Kazakhstan had ceased to become a reliable trading partner, according to Human Rights Watch.

"A country that violates fundamental human rights is not a good environment for economic investment," Hugh Williamson, the director for Europe and Central Asia at Human Rights Watch, said in The New York Times.

Mr Nazarbayev, however, criticized global expectations Kazakhstan could easily and seamlessly transform into a perfect democracy in just a decade or two.

"The glass is half full. Democracy is not the start of the path for us but the end," Reuters News quoted the president as saying.

In October, Germany likewise signed a similar agreement with Mongolia. Such agreements reflect Germany's efforts to maintain ample stockpiles of rare earths and other raw materials, but also possibly challenge China's dominant position in production of the metals.

Kazakhstan is the world's leader in uranium production. It was only recently that it began to exploit and explore its rare earths deposits.