The U.N. embargo since 1990 have been efficient in only one quarter of the cases, the new study said.
The report, compiled by The Stockholm International Peace Research Institute and the Uppsala University Special Program on the Implementation of Targeted Sanctions, said U.N. arms embargoes have had limited impact on both the compliance of targeted countries and the arms that flow to them.
The study looked at 27 U.N. arms embargoes imposed between 1990 and 2006, including the cases of Iraq, Iran and Taliban-controlled Afghanistan as well as African countries such as Liberia, Rwanda and Sierra Leone.
"There appears to be a correlation between the imposition of a U.N. arms embargo and improved target behavior in only a quarter of the annual observations made for the 27 mandatory U.N. arms embargoes studied," it said.
This was in spite of the arms embargo being "one of the most frequently used forms of sanctions" to maintain international peace and security, it said.
The main problems were listed as corruption, sanctioned targets still having access to arms within the country itself and neighboring and other embargoed countries helping each other secure arms supplies.
In cases where U.N. peacekeepers were present, however, the restrictions were respected more, it said.
To improve the effects of arms embargoes, the report proposed to the U.N. Security Council a set of recommendations including getting countries to criminalize violations, target those that assist in violating them as well as conducting regular reviews of compliance.
The companies involved in the implementation of the Nord Stream-2 project may deal with restrictive measures against them, a spokesman for the US Department of State said