A major exercise will take place in London on Tuesday and Wednesday to ensure the UK is prepared to deal with terrorism.
It comes as security is stepped up around key possible targets, such as Wimbledon and army barracks.
The Metropolitan Police led counter-terrorism training exercise in the UK capital. It was a pre-planned in the wake of the Charlie Hebdo attack in France in Janaury.
A No 10 spokeswoman, asked about disruption, said: "People will be aware of it."
It came as two suspicious packages found in Exeter city centre have been "made safe" following assessment by bomb disposal experts.
Devon and Cornwall Police were called at 6.55am on Monday after a suspicious package was discovered at a primary school.
Caretaker Brent Hibbs found the package on the railings of St Sidwell's School and alerted police after he saw wires when he looked inside it.
A second package was discovered at a car park on nearby King Williams Street - close to Exeter Mosque - at 9.15am.
A "full multi-agency" response was launched, involving police, bomb disposal experts, fire and ambulance services and Devon County Council.
Both of these packages were safely dealt with.
Elsewhere, damage was caused to graves in a Muslim section of a cemetery in the wake of the Tunisia terror attack has been condemned as an attempt to divide communities.
Nottingham City Council said it was treating the damage to at least ten plots at High Wood Cemetery in Bulwell as a hate crime.
Nottinghamshire Police has stepped up patrols at the cemetery and other sites after name plaques and decorative lights on Muslim and non-Muslim plots were damaged overnight at the weekend.
The Council's Deputy Leader, Graham Chapman, said: "We totally condemn what has taken place at High Wood Cemetery.
"This irresponsible act of hatred achieves absolutely nothing.
"We will be increasing security at the cemetery and, although we cannot guarantee solving this hate crime, the council will be working with the police to do our utmost to track down the perpetrators."
Confirming that the focus of the damage appeared to be on Muslim graves, Chief Superintendent Mark Holland said the incident was obviously very upsetting for the families affected.
He said: "Nottinghamshire Police has been liaising closely with the Muslim community in Nottinghamshire since the events in Tunisia and we have been in close contact following the reports of these events.
"I am sure everyone in Nottinghamshire will be united in their condemnation of these actions and we would urge anyone who knows anything about this incident to contact police immediately."
Anyone with information which could identify those responsible for the damages is asked to call Nottinghamshire Police on 101.
Wasim Chaudry, whose mother-in-law's grave was desecrated just three weeks after her death, said he felt "absolute disbelief" at the damage.
The 41-year-old digital communications officer, from Basford, Nottingham, said: "They broke off the name-plate but we got off lightly compared to some of the other graves.
"Some of the others had been trampled on. I just don't know what goes through people's minds. It's unbelievable."
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