The plan is expected to be announced during a speech to the Trade Unions Congress on 10 September 2007.
Opposition Conservatives have dismissed the move as "tough talk" that would have little effect on immigration levels. Business leaders are concerned that the new rule would have a negative effect on the economy.
Currently, highly skilled immigrants -- such as those that come to Britain under the Highly Skilled Migrant Programme (HSMP) -- must show that they can speak proficient English. The new rule, if implemented, would extend that requirement to skilled workers seeking work permits under the new system.
Applicants will be required either to pass an internationally recognized English test or prove that they have learned English from a recognized institution in order to qualify for a work permit.
Home Secretary Jaqui Smith said, "Those who we welcome into the UK to work and settle here need to understand our traditions and feel that they are part of our shared national culture. They need to integrate into our country, learn English and use our language."
David Frost, Director General of the British Chambers of Commerce, is concerned about the new rules.
"In recent years migrant workers to the UK have ensured the continued growth of the economy, possessing a work ethic and skill level that many young British people just do not have," he said.
"Of course language skills are important but I would be concerned if this meant that those who want to work and help our economy grow are kept out of the country and take their skills and talent elsewhere."
The government has said that 35,000 of the 95,000 skilled migrants that entered the UK last year would have failed an English test.
Brown will also look into extending the rule to unskilled workers.