The arrests come after more than 5,700 complaints about the websites were made to the Advertising Standards Authority and Citizens Advice.
Most were linked to alleged scams over fees charged for tax return, driving licence and passport applications.
Those held last week under the Fraud Act are on police bail, trading standards officials have announced.
An awareness campaign is also being launched by the government warning people to look out for the misleading internet sites, whose URLs often contain fragments of official web addresses, such as "govuk" or "directgov".
Official government services can be found by searching on the gov.uk website.
Richard Lloyd, executive director of consumer organisation Which? said the copycat websites mislead people into paying potentially hundreds of pounds for services that should be free.
The National Trading Standards Board said it was making it "as difficult as possible" for online hoaxers to operate.
Its chairman Lord Harris said: "We have been working with search engines such as Google and Bing to remove adverts from online search results and we continue to gather intelligence across the country to help tackle this issue.
"We urge you to avoid unofficial websites which could leave you out of pocket or at risk of identity theft."
Consumer affairs minister Jo Swinson said: "It's great that it's becoming easier and more common to use the internet to order official documents such as passports or tax discs, but people should be aware of rogue websites that are out there trying to exploit them and take their hard-earned cash and even put them at risk of identity theft.
"The enforcement action which the National Trading Standards eCrime team has taken demonstrates the  government's commitment to tackling these scammers. We will not let them get away with misleading consumers."

Bernard Watt was 28 when he was shot dead in Ardoyne in February 1971.
Soldiers told the new inquest into his killing on Monday that they shot him as he was about to throw a bomb.
But acting state pathologist Prof Jack Crane told the inquest on Tuesday that the injuries sustained by Mr Watt did not support the soldiers' claims.
One soldier had said that Mr Watt dropped a bomb he was holding when he was shot, and it had exploded and "blew him down the street".
Prof Crane said there was no evidence that Mr Watt had been thrown in to the air by an exploding device.
Mr Watt's family disputes the soldiers' version of events and his widow told the inquest he had no links to paramilitaries.
The new inquest into Mr Watt's killing began on Monday, and was ordered in 2012 by the attorney general, who asked for a number of controversial Troubles killings by the security forces to be re-examined.
An initial inquest held in July 1971 resulted in an open verdict.
In February, the Ministry of Defence defended a Parachute Regiment Facebook appeal asking former soldiers for information about Mr Watt's killing.

Following two recounts, AM Byron Davies gained the seat with 15,862 votes - a majority of just 27.
Labour's Liz Evans received 15,835.
Political expert Richard Wyn Jones, from Cardiff University, told BBC Wales it was "a bitter blow" for Labour who had held the constituency for nearly 100 years. The win has taken the tally of Tory-held seats in Wales to 11.
"I'm absolutely delighted that the people of Gower have put their faith in me," Byron Davies said.
Meanwhile, Stephen Kinnock, the son of former Labour leader Neil, has become an MP after Labour held on to Aberavon.
Elsewhere, the party also held Neath, Llanelli and Swansea East.
Conservative Stephen Crabb retained his Preseli Pembrokeshire seat where he has been a MP since 2005.
Labour's Geraint Davies kept Swansea West and Plaid Cymru's Jonathan Edwards held Carmarthen East. Tory Simon Hart held Carmarthen West and South Pembrokeshire.
Five people have been arrested as part of a crackdown on websites made to look like official government sites.
[NEXT_CONCEPT]
There is no evidence that a man killed during a north Belfast riot 46 years ago was holding an explosive device when he was shot, an inquest has heard.
[NEXT_CONCEPT]
The Conservatives have won the constituency of Gower - a seat Labour has held for more than 100 years.