NANJING, China (AP) -- Taiwan's Opposition leader Lien Chan has been warned against entering any agreements with Beijing in his historic trip to the mainland.

Lien, the first chairman of the Nationalist Party or Kuomintang (KMT) to set foot on Chinese soil since 1949, when the party was toppled by the communists and fled to Taiwan, was lavished with red-carpet treatment and flowers upon his arrival in the eastern Chinese city of Nanjing on Tuesday.

"Nanjing is not far from Taipei in space, but it has been more than 60 years since my last visit to Nanjing," Lien told a crowd gathered on the tarmac, referring to the Nationalists' one-time capital.

"So, seeing you here this time, I have a feeling of regret for not seeing you any earlier.

China views Taiwan as part of its territory and has pointed an estimated 700 missiles at the democratically ruled island, making the Taiwan Strait one of Asia's most dangerous hot spots.

Tensions have been reignited by Beijing's enactment of an anti-secession law in March, which sanctioned non-peaceful measures against Taiwan should it push for formal statehood.

Taiwan's President Chen Shui-bian wished Lien well, but cautioned him prior to his arrival in China, of making any deals.

China has threatened to attack Taiwan if the self-ruled island pursues formal independence moves.

"We welcome all efforts that help normalize cross-strait relations and reduce tension in the Taiwan Strait," Chen told Taiwan businesspeople in a speech.

"But any person, group or political party without authorization should not break the law and sign any agreement or consensus with the opposite side," Chen said.

Lien arrived in China on Tuesday on a history-making trip aimed at easing tensions with Beijing which has an estimated 700 missiles aimed at Taiwan making the Taiwan Strait one of Asia's most dangerous hot spots.

His visit includes a meeting Friday with Chinese President Hu Jintao -- the first encounter between leaders of the two former foes in six decades.

Relations between the Nationalists and communists have warmed in recent years as they found a common cause in their opposition to Taiwanese President Chen Shui-bian, whose party wants formal independence.

The Nationalist leader said he hopes to promote economic ties and ease tensions with Beijing.

"We hope our friends from both sides can seize this opportunity to move forward for our mutual benefit and coexistence," Lien told reporters in Taipei before boarding his flight under heavy police protection.

Scuffles broke out at Taipei's airport between Lien supporters and egg-throwing protesters who accused him of pandering to Beijing.

The rival groups shoved, kicked and punched each other. Lien supporters, gripping flags, tried to break through a police cordon but were pushed back.

Beijing has threatened repeatedly to attack if Taiwan tries to make its de facto independence permanent or continues to put off talks on unification. China's parliament enacted a law in March authorizing military action.

Lien arrived by chartered plane in the eastern city of Nanjing, the Nationalists' former capital. He planned to pay respects at the grave of Nationalist founder Sun Yat-sen -- claimed by both sides as their hero -- before traveling to Beijing to meet Hu.

Lien was accompanied on the plane by about 150 party members.

The mainland government has been trying to isolate Taiwanese President Chen and pro-independence activists by forging ties with its former enemy the Nationalists and other opposition parties that favor eventually uniting Taiwan with the mainland.

Lien's deputy party chairman visited Beijing in March. Another leading opposition figure, James Soong, has accepted an invitation to visit the mainland and his party says he might go next month.

Chen supporters say Lien's visit plays into Beijing's attempts to isolate Chen and divide Taiwanese society.

Chen's government has threatened to charge Lien with treason if he signs any deals in Beijing without government authorization.

But the president has mellowed in recent days, saying Lien could use his tour to "toss a stone to test the water" of reconciliation.

The last time leaders of the two parties met was in 1945, when Nationalist dictator Chiang Kai-shek and Mao Zedong, then a communist guerrilla, held talks on forming a national unity government.

Those negotiations failed and four years later, the communists drove Chiang and his Nationalists to Taiwan. Chiang banned all contact with the mainland.

Taiwan has relaxed some of those restrictions since the early 1990s, and Taiwanese companies are now major investors in the mainland.

But the island still bars direct travel and trade with China for fear of domination by its giant neighbor.