The announcements came on the sidelines of the APEC summit in Papua New Guinea last week.
Tonga's memorandum of understanding on Belt and Road was followed by a reprieve of the country's debt payments owed to China.
Lopeti Senituli, a political adviser to Tongan Prime Minister 'Akilisi Pohiva, told Reuters the loan payments had been deferred for five years.
Meanwhile, the Vanuatu Daily Post reports Vanuatu signed seven different MoUs with China earlier this month, including a Belt and Road agreement.