Requirements for Visa extension Beijing?

Hi, I need to extend my L type by 30 days, I am currently staying in Beijing. I need to show evidence of sufficient funds in my bank account, does anybody know if this had to be in a Chinese bank account and be in RMB or will it be okay in a British bank account and in Pounds? The information is a little unclear and I do not want to have to open a Chinese bank account. Thanks

From - UK CITIZEN