Amnesty International calls on the government of Cuba to lift the travel restrictions on Cuban blogger Yoani Sanchez, preventing her from travelling to New York to receive an international journalism award.

"The immigration office has just confirmed that they maintain the prohibition on letting me leave the country", wrote Yoani Sanchez on her Twitter page on 12 October.

This is the fourth time that Yoani Sanchez has been refused permission by the authorities to travel outside Cuba in the past two years.

Yoani Sanchez was awarded a special citation for journalistic excellence by the board of the Maria Moors Cabot Prize, the oldest international award in journalism, for her writing on the Generation Y website, which receives 1 million hits a month.

On Generation Y, Yoani Sanchez writes about daily life in Cuba. She was due to accept the award on Wednesday at Columbia University, in New York city.

"The Cuban authorities often routinely deny exit visas and bar from leaving their country those who, like Yoani Sanchez, express critical views of the government," said Amnesty International’s Kerrie Howard, Americas Programme deputy director.

"Restricting freedom of movement by denying an exit visa to Yoani Sanchez constitutes an unnecessary punitive measure for the peaceful exercise of her right to freedom of expression and association," Kerrie Howard said.

In May, the Cuban authorities denied Sanchez permission to fly to Madrid to accept an award for digital journalism.

She is known as an outspoken advocate for freedom of expression and unrestricted access to internet. Her blog, Generation Y, has been intermittently blocked by the authorities and cannot currently be read within Cuba.