Chief Executive Leung Chun-ying has hit back at criticism that he allowed the mainland to interfere in Hong Kong affairs by asking the central authorities to help in the rescue.
Leung also came under fire for visiting survivors at Queen Mary Hospital with Li Gang, the central government's liaison office deputy director.
Leung had announced he would liaise with Guangdong and ask officials to send rescue vessels while the search operation was under way on Monday night.
Yesterday, he said that as the accident involved life and death, he was prepared to mobilize all forces regardless of source - whether from the mainland or foreign countries.
Leung stressed that mainland rescue ships were only in standby support of local operations.
He said even if the SAR had used the mainland ships, they would be under Hong Kong command.
The four rescue vessels from Guangdong arrived at the scene at 4am, and were placed under the command of the marine police.
They left the area off Lamma Island in the afternoon, apparently without being pressed into service.
When Leung was asked why Li had made a high-profile appearance and joined him on visiting victims, the chief executive said Li had sought his permission beforehand.
About 1,000 emergency officers were thrown into action to rescue passengers after the Lamma IV sank off Yung Shue Wan.
Security minister Lai Tung-kwok said firefighters and police deployed 990 officers to the scene, and five government helicopters hovered above the area.
Lai said the search and rescue was extended to waters in the southern region.
During the night, helicopters lit the area with spotlights.
Around 3pm yesterday, cranes were brought in to raise the partially submerged vessel.