They come ahead of presidential and parliamentary elections on Taiwan in which the independence-leaning Democratic Progressive Party (DPP) is favoured to win, something Beijing is desperate to avoid.
The Nationalists, also known as the Kuomintang (KMT), retreated to Taiwan after losing the civil war to the Communists, who are still in charge in Beijing.
China has never renounced the use of force to bring what it considers a breakaway province under its control.
But while bilateral trade, investment and tourism have blossomed – particularly since Ma and his KMT took power in 2008 – there is deep suspicion on both sides and no progress has been made on any sort of political settlement.
“I am here to promise to everyone, we must be doing our best to reach the goal that we set previously, making the Taiwan Strait more peaceful, making the two sides more cooperative,” Ma told reporters before boarding his flight to Singapore.
Ma, chatting to reporters on board, as Taiwan air force jets escorted his aircraft out of Taiwan air space, said he was neither too nervous nor too relaxed about the meeting.
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“This is an important task. We need to do well at every stage,” he said.
No agreements are expected in what is seen as a highly symbolic get-together at a luxury hotel in Singapore, a largely ethnic Chinese city-state that has maintained good ties with both for decades.
China’s official Xinhua news agency said Xi and Ma would “exchange views on promoting the peaceful development of cross-Strait relations and discuss major issues in deepening cross-Strait cooperation and improving people’s welfare”.