Armitage, 28, was suspended from the England Saxons elite player squad after being arrested on suspicion of assault, the Rugby Football Union said.
London Irish back Armitage was detained by Devon and Cornwall Police following an incident in a nightclub early on January 29, according to an RFU statement. He was later released on bail.
Armitage, who has won 26 caps, started at full-back when England Saxons beat the Irish Wolfhounds 23-17 in Exeter on Saturday.
In a statement, the RFU said Armitage had been detained by Devon and Cornwall Police early on Sunday.
The RFU said: "The London Irish full-back was released from the England Saxons camp following the international match against the Ireland Wolfhounds on January 28.
"He was later arrested in Torquay on suspicion of assault following an altercation in a nightclub, interviewed and then released on police bail while inquiries continue."
A statement from Devon and Cornwall police read: "In the early hours of Sunday the 29th January 2012 a 28-year-old man from the Middlesex area was arrested in Torquay on suspicion of assault following an altercation in a local nightclub.
"The man was taken to Torquay police station and interviewed regarding the incident. He was later released on police bail until 21 March 2012 while investigations continue.
"A local man received a split lip during the incident but did not require medical treatment."
Armitage's arrest comes in the same month that Harlequins scrum-half Danny Care was told he would not be considered for England Six Nations selection this season.
Care was arrested for drink-driving on New Year's Day. He subsequently appeared before Southampton magistrates, where he admitted a drink-driving charge. He was fined £3,000 and banned from driving for 16 months.
England's interim coach Stuart Lancaster said: "We take issues surrounding the behaviour of England players very seriously, and as such have decided to suspend Delon from the Saxons EPS pending the result of the police inquiry.
"We will then consider if further action is appropriate under the EPS code of conduct.
"High standards of behaviour are required from England players on and off the field, and they also need to understand that they should not put themselves in a potentially vulnerable position or environment."
Armitage's club London Irish also released a statement following their player's arrest.
"London Irish is extremely disappointed to hear about the incident involving Delon while on an England Saxons release period, and takes these matters extremely seriously," the Aviva Premiership club said.
"We fully understand the RFU stance on this matter, and will convene our own internal investigation to procure a full understanding of the matter in question, the outcome of which will determine any further action.
"Player conduct is a direct representation of the club and, therefore, inappropriate conduct will be strongly acted upon."
Armitage was banned on four separate occasions in 2011.
The England World Cup squad member was suspended for eight weeks after he pushed a doping officer following a Premiership game between London Irish and Bath last January.
Then he received a three-week punishment for striking Northampton fly-half Stephen Myler, and he also collected a one-match ban during the World Cup campaign in New Zealand after a high tackle on Scotland full-back Chris Paterson, ruling him out of England's quarter-final defeat against France in Auckland.
Armitage was then hit with a five-week suspension for a dangerous tackle on Bath wing Tom Biggs, and a three-week ban for kneeing Bath lock Dave Attwood in the same game ran concurrently, sidelining him for Irish's opening two Heineken Cup fixtures this term.
England's World Cup campaign, meanwhile, was blighted by on and off-field problems.
Centre Mike Tindall was fined £25,000 and thrown out of England's elite player squad following his behaviour during a night out in Queenstown, although he later gained squad reinstatement and had the fine reduced by £10,000 on appeal.
His fellow centre Manu Tuilagi received a £3,000 RFU fine for jumping off a ferry into Auckland harbour, with Chris Ashton and James Haskell each receiving suspended £5,000 RFU fines for behaviour towards a Dunedin hotel worker.