Washington: The United States has slapped sanctions on Chhota Shakeel and Ibrahim Tiger Memon, two top aides of underworld don Dawood Ibrahim, the alleged mastermind of the 1993 Mumbai bombings that left over 250 dead, in a move "to target the nexus of crime and terrorism in South Asia".

The treasury department Tuesday designated the two as narcotics traffickers citing their ties to "D Company," which it called "one of the world's most notorious criminal organizations" that is run by kingpin Dawood Ibrahim, who is believed to be currently residing in Pakistan.

As a result of the US sanction, Shakeel and Memon will have any assets under US jurisdiction frozen. In addition, US citizens are prohibited from entering into transactions with the pair.

"Treasury continues to target the nexus of crime and terrorism in South Asia with today's action against one the world's most notorious criminal organizations," said Adam Szubin, director of treasury's office of foreign assets control, in a statement.

According to the treasury, Dawood Ibrahim's lieutenant Shakeel coordinates D Company activities with other organised-crime and terror organizations.

And Memon, a "trusted lieutenant" controls the organization's businesses across South Asia and is wanted by Indian authorities for his involvement in the 1993 Mumbai bombings, it said.

Interpol has issued provisional arrest warrants or "red notices" for both Shakeel and Memon, who are Indian nationals.

As D Company leader, Dawood Ibrahim was named as a Specially Designated Global Terrorist in October 2003, and in June 2006, he was named by the President as a Significant Foreign Narcotics Trafficker.

The treasurt said Dawood Ibrahim and his organization have been involved in international narcotics trafficking activities since the late 1980s. Their smuggling routes include South Asia, the Middle East, and Africa. Drug trafficking activities of D Company include the smuggling of heroin and hashish from Afghanistan and Thailand to the US, Western Europe, the Middle East, Latin America, and Africa.