The National Hi-Tech Crime Unit (NHTCU) has advised businesses to ensure they have the technology in place to counter attacks on their websites.
The warning came after high-profile distributed denial of service attacks on the owner of Milliondollarhomepage.com last week.
Alex Tew, the British student, and now millionaire, who owns the website, was targeted by extortionists who threatened to bombard his site with data unless he paid a ransom of £2,800.
A series of e-mails that followed increased the ransom to £28,000.
An NHTCU spokesman said, "Companies that are hit by distributed denial of service attacks should contact their internet service provider for technical solutions to survive the attack.
"A lot can be put in place. Some solutions could result in a degradation in service, but at least there would still be a service. It is a trade-off between good security and good business.
"If companies then also receive an extortion demand they should report it to their local police force."