The attack on a busy street in Hong Kong's Kowloon area injured 30 people
Police in Hong Kong say a man arrested after an acid attack on Saturday has been ruled out as a suspect.
Officers say the man was wanted in connection with a completely unrelated offence and had not been involved in the attack.
About 30 people were injured when two bottles of acid were hurled into a busy street market in the Kowloon area.
It was the latest in a number of such attacks in recent months, in which more than 100 people have been injured.
The man arrested over the latest incident had been found hiding on a roof near Temple Street night market in Yau Ma Tei, with lids that fitted the bottles thrown, a police spokesman said.
The police now say the arrested man had no involvement in the attack, but has been charged with deception in another case.
Local media are reporting he is either a white-collar worker wanted for alleged fraud or an illegal immigrant with fake identity papers.
The BBC's Anne Marie Evans in Hong Kong says police are frustrated there have been no leads in at least six acid attacks during the past year.
This time they have offered a reward of HK$300,000 ($39,000; £24,000) for any information.
Our correspondent says this last attack has left police "stumped" and fearing the acid attacker will strike again.