North Korea has received birthday greetings to its leader Kim Jong Un from U.S. President Donald Trump, but their personal relationship is not enough for a return to talks, according to a statement published on Saturday by state news agency KCNA.

While Kim could personally like Trump, he would not lead his country on the basis of personal feelings, Kim Kye Gwan, an adviser to the North Korean foreign ministry, said in the statement.

"Although Chairman Kim Jong Un has a good personal feelings about President Trump, they are, in the true sense of the word, 'personal'," he said.

"We have been deceived by the United States, being caught in the dialogue with it for over one year and a half, and that was the lost time for us."

North Korea will not discuss proposals such as those Trump made at his last summit with Kim Jong Un in Hanoi in February 2019, the adviser said.

North Korea will not give up its nuclear facilities for partial sanctions relief, and will only return to talks when the United States makes concessions, he added.

"The reopening of dialogue between the DPRK and the U.S. may be possible only under the condition of the latter's absolute agreement on the issues raised by the former, but we know well that the U.S. is neither ready nor able to do so," he said.

The abbreviation DPRK refers to the North's official name, the Democratic People's Republic of Korea.

The adviser also warned South Korea to steer clear of relations between the North and the United States.

South Korea should not intervene in the two nations' ties as if seeking "to play a mediator role," he said.

On Friday, a South Korean official said Trump had asked the South Koreans to pass a message of birthday wishes to North Korea.

"It is somehow presumptuous for South Korea to meddle in the personal relations between Chairman of the State Affairs Commission Kim Jong Un and President Trump," said the North Korean advisor.

The North had already directly received from Trump a letter with the greetings, he added.

"But they seem not to know that there is a special liaison channel between the top leaders of the DPRK and the United States," the adviser said.