I am an international student in UK. I want to apply for Schengen visa from Italy and I have to submit bank statements of last three months. I have online bank statements of last three months. Is it ok if I submit the print copy of these online statements?
Assuming that as a foreign student, your primary source of income / financial support is in a bank in your home country, online statements will likely be your only source of documentation. These are usually acceptable, but be sure to print out the entire document.
If you want to go a step further, you might try asking your country's Embassy in the UK if they offer any attestation services. They won't confirm that the money is there, rather they will attest that you swore an oath before them that the bank statements are true.
If your accounts are in the UK, as the others said, just go to the nearest branch and get a proper print out.