The United States will unveil $US300 million ($A336 million) in new aid initiatives for Afghanistan as the war economy winds down and global troops withdraw.

The programmes will be announced on Monday and are being rolled out by the US Agency for International Development.

The first tranche of some $US77 million ($A86 million) aims to enhance trade and fiscal sustainability to support Afghanistan's accession to the World Trade Organization later this year.

"Peer-reviewed articles suggest that if countries like Afghanistan make the regulatory reforms required to achieve WTO accession, they will typically see a net jump in GDP of 20 per cent within the first five years," a State Department official told AFP.

The programme will help support trade deals with Central Asian republics and India, and aid the government to boost its revenues through implementing such things as value added tax.

A second, $US92 million ($A103 million) five-year programme will help develop a more skilled workforce, partnering American universities with 10 Afghan universities. This went into force on January 1.

The third initiative worth some $US120 million ($A134 million) will support Afghanistan's agriculture sector, focusing especially on areas such as wheat and livestock, improving job opportunities and food security.

"Among other things, this programme is expected to eventually benefit 400,000 farmers from access to better technology and marketing and produce a 20 per cent increase in yields for wheat and target crops," the official said.

News of the programmes come as Congress has conditioned further aid assistance to Afghanistan on the signing of a bilateral security deal to guarantee the presence of US troops after all combat forces pull out this year.

More than 50,000 combat troops from the US-led NATO force are due to leave by the end of 2014.

But Washington is proposing that around 10,000 US soldiers are deployed from 2015 to train and assist Afghan security forces in their battle against Taliban militants.

German Foreign Minister Frank-Walter Steinmeier arrived Sunday in Afghanistan on an unannounced visit and urged President Hamid Karzai to sign the long-delayed security pact with the United States.