The United States has widened its sanctions against Iran to include 10 “shipping and front companies” accused of helping Iran's effort to advance its missile programs and transport military cargoes.

The U.S. Treasury Department announced the penalties on Tuesday, saying the companies and a Malta-based individual have ties to the Islamic Republic of Iran Shipping Lines , an entity that is already facing international sanctions.

Treasury undersecretary David Cohen said the shipping line and its subsidiaries had continued “deceptive efforts to escape the grasp of U.S. and international sanctions.”

The new penalties target Malta-based firms and Jamshid Khalili, an Iranian national who heads the Irano Hind shipping company. The measures deny the firms and Khalili access to U.S. financial and commercial markets.

The U.S. announced the new measures as Italy hosted diplomats from a number of nations to discuss possible further penalties against Tehran related to its suspected program to develop nuclear weapons. News agency reports say the group of “like-minded countries” discussed Iran's oil and energy sectors.

The diplomats included representatives of the U.S., EU and several individual European nations along with Japan, South Korea and Australia.

In November, the U.N.'s nuclear watchdog agency expressed “deep and increasing concern” about Iran's nuclear activities. Earlier in the month, the IAEA said there was “credible” evidence that Tehran is trying to build nuclear weapons.

Iranian authorities say their nuclear program is peaceful. On Tuesday, Reuters news quoted Iran's IAEA envoy, Ali Asghar Soltanieh, as saying his country had invited the watchdog agency for talks concerning its nuclear ambitions. There was no immediate response from the agency.