Xi added that Moon's decision to send his special envoy to Beijing after his inauguration demonstrates how much importance he is placing on the relations with China and noted that China also places as much importance as South Korea does on their bilateral ties.

He also expressed hope for normalizing their ties "as soon as possible" by resolving differences based on mutual understanding, respect and trust.

Delivering Moon's letter, Lee said that he was asked to express gratitude on his behalf for Xi's congratulatory phone call and message following his election and inauguration last week.

Lee's visit to China came amid Beijing's continued protest against South Korea's decision last year to allow a U.S. missile defense system called THAAD to be installed on its soil.

China has taken what appeared to be retaliatory steps against South Korean companies in diverse areas, apparently in a bid to put pressure on South Korea to withdraw its plan for the THAAD installation, which it sees as a threat to its own strategic security interests.

Lee, who served as prime minister under the Roh Moo-hyun government from 2004-2006, embarked on his trip to Beijing on Thursday when he met with Chinese Foreign Minister Wang Yi.

Wang told him that he hoped South Korea's new government will take measures to "remove the obstacles" in order to improve their bilateral relations.

Earlier in the day, Lee also met with Chinese State Councilor for Foreign Affairs Yang Jiechi, who told the South Korean envoy that the meeting was an important opportunity for Beijing-Seoul communication and that China is willing to keep exchanging views with South Korea on issues of mutual concern.

Some are cautiously raising hopes that both countries might be moving toward mending their ties frayed over the THAAD issue, with China apparently easing some restrictions on South Korea taken in retaliation.

During his stay in Beijing, meanwhile, Lee is expected to discuss key pending issues with China, including the THAAD controversy, cooperation against North Korea's nuclear threat and near-future summit talks between the two countries. Before leaving for Beijing on Thursday, Lee told reporters in Seoul that Moon and Xi could meet first on the sidelines of a Group of 20 gathering to be held in Germany in July. (Yonhap)