And they are asking the public to contact them in other ways, to free up the service more serious incidents.
But after police made the request on their Facebook page on Saturday, some people said they wouldn't resort to using it if the 101 response was faster.
On their social media page, the police stated: "We are currently experiencing a very high volume of calls in to our control room are asking that you only use 999 in an emergency.
"Non-emergency incidents can be reported online here: http://orlo.uk/EVSXq."
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But one disgruntled man posted: "If you didn’t have to wait hours to get through on 101 by which time the non urgent crime has take place and the offender is long gone to then be told you are too busy to attend then people wouldn’t use the emergency number.
"People are sick of reporting and nothing happening."
Assistant Chief Constable Pete Lawson, of Lancashire Police, said: “We have had a huge number of calls in to our control room already today, and we are expecting thousands more before the end of the weekend.
“We are now asking people to think about how best to get in touch with us, and to use the online reporting facility if appropriate.
“Our control room operators do a brilliant job, working efficiently and professionally to help keep everybody safe, but please do your bit and only call 999 if it is a genuine emergency.
“We know a lot of people (including us!) will be looking forward to the football tomorrow - maybe with a few drinks – or getting out and about with friends or family this weekend. But please also be mindful of keeping yourself and others safe to help reduce demand on emergency services.”