'The United Nations allows signatory countries to make reservations on certain clauses and Chinese officials have pointed out that the situation in the country will not allow China to adapt to the three clauses at this stage,' the source said.

China is scheduled to sign the covenant on Monday .

A National People's Congress legislator said: 'We'll need to ratify the constitution if we are to consider expanded freedom in the area of free association. But at this stage, the country's leaders have given priority to political stability instead of changes in political freedom.' The Government has rejected attempts to register opposition parties.

'The crime situation in the country also makes it impossible to restrict the use of the death penalty,' said the legislator.

Though the authorities will continue to limit the movement of people from rural areas to cities by using its long-standing urban permanent residence system, another Beijing source said a revised regulation that took effect two months ago had relaxed restrictions.

The revised regulation, put through by the Public Security Ministry, allows people to acquire permanent residence in a city if they have investments or have bought flats there. Elderly people in villages whose children have moved to cities will be allowed to join them for the first time.

Rural spouses living apart from their urban-based husbands or wives can also apply to be transferred to cities.

'Such a revised regulation is passed to get closer to the spirit of the UN Covenant on Civil and Political Rights, but this is the furthest the Government can go,' the source said.

The pressure of the huge population and the limitations of urban facilities would not allow the mainland to go as far as the degree of freedom listed by the covenant, he said.

The announcement that China would sign the covenant has sparked a flurry of attempts by dissidents on the mainland to push for political reforms, the release of political prisoners, and press freedom and judicial independence.