The chairman of the Home Affairs Select Committee has called for improved cyber security after it was revealed there have been 90 million suspicious events on the National Crime Agency website since October 2013.
There were also 178 significant DDoS (distributed denial-of-service attacks) on the website over that period, which means an attempt to make a machine or network resource unavailable to its intended users.
The information was supplied in a letter from the agency's director general, Keith Bristow, to the committee.
Mr Bristow said they were a "blunt form" of attack which took volume and not skill.
"It is not a security breach, and it does not affect our operational capability.
"The measures we have in place at present mean that our site is generally up and running again within 30 minutes, though occasionally it can take longer. We consider that this is proportionate."
The website has experienced nearly 90 million intrusion detection sensor events since October 2013. An intrusion detection sensor monitors network traffic and flags potential suspicious activity.
Committee chairman Keith Vaz said: "The extraordinary figures revealed by the National Crime Agency demonstrate the significant challenge, and scale, of cyber crime today. Modern policing has truly changed.
"Following the Chancellor's decision to provide extra funding of £1.9 billion for the UK's National Cyber Security Strategy, we need to know how much will be allocated to protecting us from attacks like this.
"It is vital that we not only bolster our cyber security, to prevent attacks like the one on TalkTalk earlier this year, but that we are more aggressive in going after cyber criminals and terrorists using the internet for recruitment, financing and to spread propaganda."