Gordon Brown is to announce tighter controls on would-be migrants coming to work in the UK, in a move which could cut arrivals by 35,000 a year.

The Prime Minister will say that tens of thousands more migrant workers must pass English language tests before coming to the UK.

The controversial clampdown, to be unveiled in a speech to the TUC annual conference in Brighton today, will affect skilled workers from outside the European Union, the Sunday Telegraph reported.

Under the Government's current points scheme, migrant workers from outside the EU are split into three groups - highly skilled, skilled and low-skilled.

Of these, only the highly skilled and skilled categories are permitted to seek permanent residence in Britain.

Since last December, highly-skilled migrants have had to show proficiency in English as a condition of entry.

Mr Brown and Home Secretary Jacqui Smith will announce today that the requirement is to be extended to all those in the skilled category.

They will be expected to speak, write and understand English to a standard equivalent to GCSE grade A-C. To prove eligibility they will have to show they have passed an internationally recognised English test or obtained a university degree from a course taught in English.

The paper quoted government sources as saying that about 35,000 of the 95,000 skilled workers who came to the UK last year would not have passed an English test.

Mr Brown and Ms Smith will also announce a review on extending the English language requirement to cover low-skilled workers, even though they are not be allowed to apply to settle permanently in the UK.

Ms 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.

"At present, people who seek to come to the UK permanently, or as highly skilled workers, are required to speak English.

"I want to go further and make speaking English a requirement for all those coming in to the UK to do lesser skilled work and I will be looking at extending this requirement to those who come to the UK to do low-skilled work as well."