Standard visitor visa for father - bank statements?

[trplex]

Hi all,
I am in the process of applying for a standard visitor visa for my dad from India. My husband and I are both British citizens and we will be sponsoring his entire trip - including visa fee and flights. We own a three bedroom house in the UK. We have stable jobs and enough funds to sponsor his trip. We will be submitting our 6 months' payslips and bank statement. My mum and sister have previously visited us in the UK.
My dad is a retired government official with a steady pension (1000GBP per month). However, his bank account shows large transactions as he manages my mum's business. He also uses the sweep in credit facility in his bank account which makes his balance show as negative at times. He lives with my mum, sister and brother in law and owns a house as well as landed property which would show ties to his home country.
Please could you let me know if it is sufficient for him to show papers confirming his assets (property) plus money (about 3000GBP)? Does he HAVE to submit his bank statements?
Many thanks!