Birth certificate required for I-134 co-sponsor for K1?

[sanbot 5]

I've read a few posts now saying that a birth certificate is needed for the co-sponsor to prove their US citizenship. But nowhere on the I-134 instructions does it state this?

So can anyone confirm if its required or not for the US Consulate in Sydney?

[charlottelizabeth 11]

I included a copy of my co-sponsors BC as well as a copy of their ID. I'm not certain it's 100% required (a copy of their American passport is usually enough to prove US citizenship) but I liked to know I was covering all the bases.

[sanbot 5]

For anyone interested, I didn't end up having to provide the birth certificate for the co sponsor.