"Both sides will have in-depth exchanges on China-Iran bilateral relations and international and regional hotspot issues of mutual concern," foreign ministry spokesman Guo Jiakun said.

The visit to China by Tehran's top diplomat comes ahead of a third round of nuclear talks between Iran and the United States.

Araghchi previously visited China, which was a signatory to a since-abandoned 2015 agreement that reigned in Tehran's nuclear programme, in December.

China is Iran's largest commercial partner and the main buyer of its oil, with Tehran still under crushing US sanctions.

Around 92 percent of Iranian oil heads towards China, according to Iranian media, and is often sold at a considerable discount.

In 2021, Tehran and Beijing signed a comprehensive 25-year strategic agreement covering energy, security, infrastructure and communications among other areas.

China on Tuesday hailed its "traditional friendship" with Iran.

"The two countries have maintained mutual respect, trust, and support, promoting the healthy and stable development of bilateral relations and contributing to regional and global peace and stability," Guo said.

The 2015 accord, formally known as the Joint Comprehensive Plan of Action (JCPOA), was also signed by four other permanent UN Security Council members -- Britain, France, Russia, and the United States -- along with Germany and the European Union.

US President Donald Trump withdrew from the agreement in 2018, during his first term, which prompted Iran to breach its terms a year later.

Since returning to office in January, Trump has called for nuclear talks with Tehran while at the same time threatening military action.

Western nations have long accused Iran of pursuing nuclear weapons, something Tehran denies.

The Iranian foreign ministry said earlier this week that Araghchi's visit would start on Tuesday, though China said it would be on Wednesday.