Taiwanese President Chen Shui-bian has rejected a fresh definition of relations with China offered during an opposition leader's visit to Beijing.
Hu Jintao and James Soong pledged to end hostilities
Mr Chen said the "two sides, one China" formula did not amount to any concession by the Chinese leadership.
His remarks came as James Soong, the head of Taiwan's opposition People First Party (PFP), ended his visit.
Mr Chen opposes the "one China" policy agreed in 1992, saying it would undermine Taiwan's sovereignty.
"China did not make any concessions," he said on Taiwanese TV. "China's basic attitude has remained the same."
But the BBC's Francis Markus says there will now be strong pressure on Taiwan's government to soften its stance on preconditions for talking to China itself.
China no doubt hopes that even if Mr Chen remains entrenched, the dialogue with the opposition will boost their chances of recapturing Taiwan's presidency in 2008, he says.
Mr Soong left Beijing on Friday morning, a day after holding talks with Chinese President Hu Jintao.
He left as Chinese officials offered to ease restrictions on employment and study for Taiwanese residents on the mainland.
At their meeting Mr Hu praised his guest for the PFP's opposition to Taiwanese independence, and said that cross-strait relations were at a "crucial moment".
Mr Soong said the world was watching to see what progress the two could make.
The men then issued a joint statement pledging to work together to end hostilities between Beijing and Taipei.
The statement was virtually identical to one issued by Mr Hu and Lien Chan, leader of Taiwan's biggest opposition group, the Nationalist Party, who also visited Beijing recently.
Both opposition parties favour Taiwan's eventual reunification with China, as long as it is by then democratic.
Both opposition leaders have been feted by China during their trips to the mainland.
And even if the dialogue that has been opened up is not with Taiwan's elected government, it still forms a new channel of political contact where there was none, our correspondent says.
Taiwan's National Assembly elections on Saturday are likely to be seen as an important gauge of how China's charm offensive is playing with the island's voters.