Macau VISA exemption

I have been advised by local VISA support agencies that travelers from our company in Washington State, who are entering Macau and will be supervising on a job site for less than 30 days do not require a VISA – that a passport is sufficient for entry.

Please confirm if this is correct.

We expect they will be entering on Sept. 17, 2012 and leaving on Sept. 30, 2012.

Thank you in advance for your prompt reply.