Tsai took the presidential oath of office on Friday at the Presidential Office Building in the capital, Taipei, after winning a landslide victory in January.

The president sought to cast Taiwan as a cross-strait peacemaker. Beijing has sought recently to portray the new government as a source of instability.

"The two governing parties across the strait must set aside the baggage of history, and engage in positive dialogue, for the benefit of the people on both sides," she said.

"Cross-strait relations have become an integral part of building regional peace and collective security," she told the audience of 20,000. "In this process, Taiwan will be a 'staunch guardian of peace' that actively participates and is never absent."

Moving away from Beijing

Her Democratic Progressive Party's defeat of the ruling Kuomintang (KMT) ended an eight-year rapprochement with Beijing under outgoing president Ma Ying-jeou.

China - which claims Taiwan as its own territory - has responded to the election of Tsai by intensifying pressure.

Chinese pressure tactics in recent months have included the deportation of Taiwanese fraud suspects to the mainland from Kenya and Malaysia, infuriating Taipei.

Many voters felt Ma had moved too close to China.

What Beijing wants, Beijing gets

Beijing has said it wants Tsai to publicly acknowledge its message that there is only "one China," a concept enshrined in an unspoken agreement with the KMT known as the "1992 consensus."

Taiwan split from the mainland in 1949 after a civil war but has never declared a breakaway.

Recognition of that agreement formed the bedrock of the thaw under Ma, but Tsai and her DPP have never backed it.

Tsai has pledged to maintain the "status quo" with Beijing, but observers say she is highly unlikely to show any sign of compromise on the "one China" issue during her speech.

Voters will also want to hear how Tsai will revive Taiwan's ailing economy and be reassured that the island's sovereignty will remain secure.

jbh/kl (AP, AFP, dpa)