The Obama administration has announced that it will put more pressure on Iran’s oil industry as US lawmakers drafted a new bill of sanctions, reports the Financial Times.

The new sanctions are aimed at penalising banks which handle transactions for the National Iranian Oil Company (NIOC) or its trading subsidiary, Naftiran Intertrade Company (NICO). China’s Bank of Kunlun and Iraq’s Elaf Islamic Bank have been identified by the Treasury department so far.

The new measures come after Republican presidential candidate Mitt Romney claimed that the White House was not doing enough to deter Iran’s nuclear ambitions. Israeli prime minister Benjamin Netanyahu said that existing sanctions have not worked. In contrast, US officials said that a European ban and US sanctions were already having a “crippling” effect on Iran’s oil revenues after major Asian consumers were forced to cut back their imports.

According to Robert Einhorn, a senior state department official for non-proliferation and arms control, Iranian oil exports have decreased by 40-50% to 1m barrels per day this year. He added that “the Obama administration is determined to increase the pressure on Iran until it is willing to negotiate seriously.”