UNITED NATIONS — China's president on Saturday pledged billions in aid and said Beijing will forgive debts due this year in an effort to help the world's poorest nations, as world leaders begin to seek the trillions of dollars needed to help achieve sweeping new development goals.

President Xi Jinping spoke at a global summit that on Friday launched the non-binding goals for the next 15 years.

Xi and others spoke as the U.N. gathering began to shift focus from development to the high-powered General Assembly meeting that begins Monday with speeches by Xi, President Barack Obama, Russian President Vladimir Putin and Iranian President Hassan Rouhani on the first morning alone.

Obama and Putin will meet Monday. The prospects for any meeting between Obama and Rouhani, even a handshake, remained unclear.

Rouhani arrived Saturday and immediately was encouraged by U.N. Secretary-General Ban Ki-moon to have Iran step up to help achieve political settlements to the grinding conflicts in Syria and Yemen, where Iran has influence. The Islamic republic is a top ally of the Syrian government of President Bashar Assad and supports Shiite Houthi rebels who have held parts of Yemen for months.

Iran's president said in his address that the recent deal with world powers on its nuclear program "has created suitable conditions for regional and international cooperation," including on protecting the environment.

As world leaders met quietly behind the scenes, others lined up to express support for the new development push that aimed to eliminate both poverty and hunger over the next 15 years. They replace a soon-to-expire set of development goals whose limited success was largely due to China's surge out of poverty over the past decade and a half.

China's president vowed to help other countries make the same transformation. Xi said China will commit an initial $2 billion to establish an assistance fund to meet the post-2015 goals in areas such as education, health care and economic development. He said China would seek to increase the fund to $12 billion by 2030.

And Xi said China would write off intergovernmental interest-free loans owed to China by the least-developed, small island nations and most heavily debt-burdened countries due this year.

He said China "will continue to increase investment in the least developed countries," and support global institutions, including the Beijing-backed Asian Infrastructure Investment Bank that is due to launch by the end of the year and is seen as a Chinese alternative to the more Western-oriented financial institutions of the World Bank.

Ban made a major pitch to the private sector Saturday for its help in financing the development goals. "In a sense, September 26th is even more important than September 25th," he told dozens of global business leaders from companies including Google, Unilever, Siemens and Sinopec. "Today, we begin the hard work of turning plans into reality."

As world leaders made promises about the future, a key Jordanian leader said they needed to pay attention to the refugee crisis now spiraling out of control in the Mideast.

Jordan Minister Imad Najib Fakhoury made an impassioned plea at the U.N. summit for the world's countries to take in more Syrian refugees to help his country which has been overwhelmed by those fleeing the conflict there.

In his address, Fakhoury said Jordan's efforts are akin to the United States having to absorb 64 million more people, or the European Union 100 million, or Japan 25 million, or China 280 million.

Lebanon Prime Minister Tammam Salam made a similar plea, telling the United Nations the Syrian refugee crisis was costing his tiny country one-third of its gross domestic product and strangling development.

Salam said the Syrian civil war and fleeing refugees "is one of the greatest development challenges" facing Lebanon. The Mediterranean country has become home to more than 1.2 million Syrian refugees — about a third of Lebanon's native population.