The Hong Kong Special Administrative Region is getting ready to resume cross-border travel with the Chinese mainland as early as Sunday.

Customs and clearance officers have been recalled to border checkpoints, cross-boundary buses are undergoing mechanical checks after three years of being idle, and train staff have been summoned to re-familiarize themselves with their work.

Chief Secretary for Administration Eric Chan Kwok-ki revealed in a Sunday social media post that Hong Kong is striving to gradually resume normal travel with the mainland on Jan 8 at the earliest, and a quota will be set at the initial stage.

Beginning Jan 8, travelers to the mainland will no longer need to quarantine.

Local media reported that the Hong Kong government has submitted its proposal to the central government on the resumption of cross-boundary travel with the mainland and it will be made open on Wednesday at the earliest.

Citing sources, local media reported that the quota will be initially set at 30,000 to 50,000 people per day.

Lawmaker Michael Tien Puk-sun told China Daily on Tuesday that quotas will be allocated to different checkpoints to avoid crowds at any one particular spot.

Tien, a former chairman of Kowloon-Canton Railway Corporation before it merged with MTR Corp, told China Daily that ticketing services for high-speed rail between Hong Kong and the mainland will be available on Thursday at the earliest.

The number of tickets up for grabs will be up to the initial quota that is set for cross-boundary travel, Tien added.

The rail operator has arranged for staff to return to their posts at stations for cross-boundary travel, including Lo Wu and Lok Ma Chau and West Kowloon Station for high-speed rail.

It was reported that train services for short-distance routes, such as Futian, Shenzhen North, Guangzhou South, will be resumed first. Medium-range routes to Changsha of Hunan province and Xiamen of Fujian province will follow. Longhaul trips to Beijing and Shanghai will be restored after that.

In an earlier local radio program, Cheung Chi-keung, head of cross-boundary operations for MTR Corp, said that tickets would be available for sale three days before the full resumption of cross-boundary travel, online or on-site, and high-speed train services will begin trial operations on Tuesday.

MTR, in an email reply to China Daily on Tuesday, said that it had "no arrangement for trial operation of high-speed train services", without revealing reasons for the delay.

"MTR is fully cooperating with the government and liaising closely with the relevant departments to work out a plan to ensure its railroad service will gradually, orderly and comprehensively connect the SAR and the mainland," it said.

Bonnie Lo Hoi-sze, chairwoman of the Association of Customs and Excise Service Officers, said that customs officers working at the borders have been well-trained and some borders are already prepared for re-opening.

Cheung Kim-ping, vice-chairman and secretary of the Hong Kong-Guangdong Boundary Crossing Bus Association said about 200 to 300 buses can run during the initial stage and the industry is recruiting more drivers with competitive pay to meet demand.

In addition, Cathay Pacific Airways announced on its social media that it will increase its passenger services between Hong Kong and Beijing, Shanghai and Guangzhou from Jan 8, and between Hong Kong and Xiamen from Jan 14.