A roadside bomb killed a US soldier in Helmand, a province in southern Afghanistan that has seen an upsurge in violence in recent weeks.

The bomb also wounded another US soldier and six Afghan soldiers, coalition forces said in a statement on Tuesday. The wounded soldier was in stable condition, the statement said.

Around 100 US troops were deployed in Helmand at the weekend to support Afghan security forces struggling to contain a resilient Taliban insurgency, the US military said.

Afghan officials in Helmand said the newly deployed US troops are helping Afghan troops to retake the area around Lashkar Gah, the capital of the province. Government troops lost the area to the Taliban in intense fighting over recent weeks.

Around 10,000 US forces are operating in Afghanistan, divided between a NATO training and assistance mission and US counter-terrorism operations against militant groups. Since international troops began to leave the country in 2014, fatalities among coalition forces have dropped significantly.

One US soldier was killed and two wounded when they came under fire in Marjah district of Helmand on January this year. Last month, five US special operations troops were wounded in an operation against Islamic State in eastern Afghanistan.

Taliban fighters have made major gains across Helmand in the past year, forcing government troops to abandon some bases and checkpoints. Afghan troops have pushed the Taliban back a few kilometers from areas near Lashkar Gah, but officials say the militants remain within four to 10 kilometers of the city.

Government forces say the Taliban have deployed a 'special forces' unit to fight Afghan forces in the front line, said to be equipped with advanced weaponry, including night vision scopes, heavy machine guns and US-made assault rifles.