The government may bow to pressure from the Chinese government not to attend next month's Nobel peace prize ceremony in Norway, where a leading Chinese dissident will receive the prestigious award.

With less than a month to go to the 10 December event, the continuing refusal by the Department of Foreign Affairs to confirm that Ireland will attend has led to calls from Amnesty International for the state to clarify its position on the forthcoming ceremony for Liu Xiaobo, a Chinese pro-democracy activist who was sentenced to 11 years in prison last December on "subversion" charges.

It says there have been informal indications that the rate of acceptance of invites to the annual ceremony is slower than in previous years, suggesting that some western diplomats are weighing up whether or not to risk alienating the Chinese government by sanctioning attendance at the event.

The failure of the Irish government to clarify its position comes as it emerged that parts of the ceremony may be postponed because Liu remains in prison and his family members have been prevented from leaving China to attend the event on his behalf. However, the event is expected to go ahead in Oslo as planned, with the formal awarding of the peace prize medal delayed until a future date. Instead, text messages from Liu and perhaps some of his past writings may be read aloud at the ceremony.

Chinese state officials are furious at last month's announcement of the decision to allocate the award to Liu, claiming he is a criminal for advocating more democracy in China.

This anger has culminated with the Chinese authorities sending letters to European embassies in the Norwegian capital asking them to shun the event. The letter also calls on embassies not to issue any public statements in support of Liu on the day of the ceremony.

Asked to clarify whether the Irish ambassador in Oslo will be attending the event, a foreign affairs department spokesman noted that an invitation to the Irish ambassador in Norway "has been received".

But he would not say whether the ambassador will attend the event, and refused to be drawn on whether the Chinese government had contacted the Irish embassy in Oslo urging a boycott.

Similarly, he would not say if foreign affairs minister Micheál Martin or his ambassador intend to issue a public statement in support of Liu on the day of the ceremony or in advance of the award.

"[The invitation] will be considered in the normal way and a response will be given in due course," he said. "The case of Liu has been raised in bilateral contacts with the Chinese authorities. The European Union has also raised it in its human rights dialogue with China."

Colm O'Gorman, executive director of Amnesty International in Ireland, said the organisation's colleagues in Oslo have heard that embassies there have been slower to reply to the Nobel prize-giving committee's invitations this year.

"That seems to be suggesting that something is happening. But the truth is, we just don't know," he said.

"We would call on the Irish government to attend the ceremony, to show its support for freedom of expression , and to defend human rights in China.

"To say that he is a worthy winner of the prize is an understatement. But he is also an example of the kinds of actions human rights defenders are taking all the time. These are the moments we find out what we're made of. Do we stand with people who are defenders of human rights, or are we concerned about not offending China?"