Washington: A Maryland man who collected cash payments from a foreign company to plot an Islamic State attack in the United States and help the group develop weaponised drones has been sentenced to 20 years in prison.

Mohamed Elshinawy, 33, of Edgewood, pleaded guilty to supporting IS, terrorism financing and making false statements in connection with a terrorism matter, according to a statement from the US attorney's office in Maryland.

Between February and December of 2015, Elshinawy conspired with others to support IS, also known as ISIS, and provide the terrorist group with financial services, material support and other resources, the government said.

"In various other conversations, Elshinawy pledged his allegiance to ISIS, described himself as its soldier, committed to making violent jihad, and asked that others convey his message of loyalty to ISIS leadership," the statement from federal prosecutors said.

A company based in the United Kingdom also transmitted about $US8700 ($11,300) to Elshinawy to pay for a terrorist attack on US soil, according to his plea agreement.