Part time work policy for Tier 2 visa holders

[sumair]

Can anybody comment with reference?

I have done some research and found following links.

http://www.ukba.homeoffice.gov.uk/visas ... mployment/


http://www.ukba.homeoffice.gov.uk/sitec ... iew=Binary

looks like Tier 2 visa holders can work part time under 20 hrs/week.
Obviously NI number will be used for payment, so I was wondering whether it has adverse effects on visa health.

Thank you.