United States President George Bush on Thursday piled on further sanctions directed at the interests of Burma's military leaders, seeking to close a previous loophole in U.S. sanctions policy.

Speaking in Washington on the commemoration of Asian Pacific American Heritage Month, Bush announced an executive order for the U.S. Treasury Department to freeze the assets of three state-owned companies in Burma.

Previously state owned entities were not covered under the lengthy U.S. sanctions regimen directed at Burma.

The companies in question are said to be predominantly involved in the gem and timber industries, described by Bush as "major sources of funds that prop up the junta".

Inclusion of the operations is seen by the President as another example of the U.S. combating the dire human rights situation inside the Southeast Asian country. The industries, according to Bush, serve merely to "exploit the labor of the downtrodden Burmese people, but enrich only the generals".

The President also took the opportunity to laud America's immigration policy and acceptance of Burmese refugees and exiles on U.S. soil.

Drawing attention to the positive work of the U.S. in already resettling tens of thousands of Burmese citizens in the U.S., Bush remarked that 2008 could witness the welcomed arrival of an additional 18,000 Burmese on American shores.

Analysts remain divided as to the efficacy of sanctions, especially those directed at the gem industry.

Gems are argued to be difficult to trace and with a relative inelastic demand. The result has been that regional dealers in the trade have reported little, if any, significant change in business since the threat and imposition of sanctions aimed at the gem trade.