The National Police Agency said Monday the drug investigation into G-Dragon was nearing the end, with no clear evidence of wrongdoing by the K-pop star discovered so far.

"We've conducted an objective verification process (of G-Dragon's allegations) and summoned six people for testimonies. The investigation is more or less in its final stage," Woo Jong-soo, the head of the National Office of Investigation at the NPA told reporters in the regular press briefing. "We will wrap things up as soon as we can and notify the results."

The 35-year-old star has been probed on suspicion of using drugs at a high-end bar in Gangnam-gu, southern Seoul in December of last year, based on information the police received while investigating drug allegations into another celebrity of international fame, actor Lee Sun-kyun.

But G-Dragon has tested negative in the detailed narcotics analysis of his biological samples, and no further evidence backing the allegations have been found.

Last month, the police lifted the travel restrictions on the K-pop icon.

Drug tests carried out on Lee also came back negative. Police are planning to summon the 48-year-old actor again for further questioning.

Officials are also investigating the blackmail charges filed by Lee. Lee claimed a hostess at a high-end bar in Gangnam extorted 350 million won from him, for reasons related to the drug allegations.