BEIJING -- Turkish President Recep Tayyip Erdogan met with top Chinese officials Wednesday amid tensions over China's treatment of its Uighur minority and sensitive negotiations surrounding the possible purchase of a Chinese missile system.

It wasn't clear whether progress was made on either issue, although both Erdogan and Chinese President Xi Jinping affirmed the strength of relations.

"The future of China-Turkey relations is very bright and has great potential," Xi said in remarks before the media at the Great Hall of the People in central Beijing.

Erdogan responded that ties were advancing and becoming ever-more substantial.

"We believe this will help strengthen mutual political trust and the friendship between our two peoples," Erdogan said.

Following a two-hour meeting, the two presided over the signing of agreements on trade, investment and boosting dialogue at the vice prime-ministerial level.

While the sides enjoy outwardly friendly relations, Turkish public sentiment has been inflamed by reports that members of the Uighur minority native to China's northwest have been restricted in practicing their Islamic faith, particularly during the holy month of Ramadan, which ended in mid-July.

Turks and Uighurs share close linguistic, cultural and religious ties.

Hundreds of people marched in Istanbul earlier this month, burning Chinese flags outside the consulate, waving flags representing the Uighurs' putative homeland and calling for a boycott of Chinese goods. The demonstration was peaceful, but a group of nationalists tried to attack a group of Korean tourists who they mistook for Chinese. Police rescued the tourists.

Prior to the protests, the Turkish Foreign Ministry had called in the Chinese ambassador and issued a statement saying the Turkish public was "saddened" by reports of the Ramadan restrictions.

China responded by denying any curbs on religious expression and demanding that Ankara clarify the matter. Despite Beijing's statements, China has exercised long-standing bans on Uighur Communist Party members, government workers and students joining in religious observances.

China has sought to enlist the support of Turkey and others in denying safe havens for Uighur activists, even those advocating peaceful opposition. Last year saw a wave of violence by Uighur extremists opposed to Chinese rule, but China has not implicated Turkey in any of those attacks.

Briefing reporters after the signing ceremony, Chinese Vice Foreign Minister Zhang Ming said Erdogan stressed Turkey's respect for China's sovereignty and territorial integrity and "will not allow anyone to use Turkey's territory to do anything to harm China's national interests and security."

He said the sides agreed to strengthen joint efforts against terrorism and people smuggling, but did not directly answer when asked about Uighurs who have left China for Turkey.

Earlier, Erdogan met with Chinese Premier Li Keqiang, who affirmed the strength of ties further complicated by Turkey's closeness with the United States and the ongoing civil war in Syria.

Turkey, a NATO member, agreed in principle in 2013 to buy China's HQ-9 air defense missile system. China reportedly offered the best price and to furnish the technology behind the system.

However, the deal has run into controversy over its incompatibility with NATO weapons systems and the possible leak of military secrets to Beijing.

Asked about the negotiations, Zhang, the vice minister, said only that the sides have "strong interests in defense cooperation and will strengthen co-operation in this area."

China has also opposed any international intervention in Syria, while Erdogan has been among the toughest critics of Bashar Assad's regime.

The differences come despite growing tourism and surging Chinese exports to Turkey, which has contracted with a Chinese company to build a high-speed rail line.