BEIJING, August 7, 2008 (AFP) - A jailed Chinese dissident has sent a letter to International Olympic Committee head Jacques Rogge, telling him prisons have worsened and urging him to go see for himself, a rights group said Thursday.

He Depu, a veteran activist serving an eight-year sentence, told Rogge that political prisoners were particularly worse off, despite hopes the Olympics would be a catalyst for change, New York-based Human Rights in China said.

'The Olympics are fast approaching,' said the letter, written in Block 17 of Beijing's No. 2 Prison in April.

'But the limitations placed on us as political prisoners in Beijing have not only not lessened, but rather have increased.'

Political prisoners are not allowed to call or meet with their families, obtain a reduced sentence or participate in recreational activities organised by the prison, he wrote.

But conditions have deteriorated for all types of prisoners, political and criminal alike, he said -- food has gotten steadily worse while medical care is inadequate, with sometimes fatal results.

'For many years, there have been two numbers that have been particularly high: the first is the number of sick prisoners, the second is the extremely high number of deaths,' the letter said.

In the run-up to the Olympics, prisoners have been put under stricter surveillance, with the jail 'study rooms' now all completely shut down, giving them no choice but to stay in their crowded cells, he said.

'I have a question for Mr Rogge: Each time you come to Beijing and see the joyous spectacles here, do you know that just ten or so kilometres away, Beijing's political prisoners are suffering immensely for the progress of society and the elevation of human civilisation?' He wrote.

'I hope that when it is convenient, you can come just once to the Beijing No. 2 Prison to see what it is like for the prisoners living here.'

He has been a democracy activist since the late 1970s, and was sentenced to eight years in jail in November 2003 after signing an open letter calling for political reform.

He has repeatedly suffered abuse while in detention, according to Human Rights in China.