I am an Australian trying to get a visa for China. I needed to get a National Police Check done and have it authenticated at the Aus embassy in Bangkok. I pick it up on Monday after just 2 days turnaround. Now the China visa service in BKK says it must be stamped by Thai MFA, in particular the Department of Consular Affairs. It does not need to be translated, China will accept it in English. 

My question is:  can anybody go to the appropriate government dept and get this done and how long does it take? I presume they recognise the Australian government authentification stamp. Or is it better to use an agent, even though there is no translation required?

Yes the service is open to foreigners as well as Thais. There is no need for an agent. It was busy not well organised 

The official rules about turnaround state that your document must be in fairly early (9.30 am I think) to get same day turnaround but i submitted mine at 11 am and got it back around 13.30, maybe because it was in English anyway. They check the quality of translated documents.  It carried an Australian embassy seal which was easily recognised.

Cost was only 400 baht and while you wait for pickup,  the food on the ground floor canteen us cheap and not bad 

Hope this helps someone else.

Footnote

A sign says a new BKK legalisation service point is now available at  Klong Toei MRT station which would save the long taxi ride to Lak Si.

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Interesting, I thought they only stamped documents in Thai at the MoFA.