Twenty arrests after post-demo clashes in Manchester
Twenty people were arrested by police after a splinter group left a rally against government spending cuts and marched to Manchester city centre.
Thousands of protesters had gathered peacefully in Platt Fields Park to hear claims from union leaders that the coalition was "betraying" young people.
But there were clashes when a group of about 150 broke away, police claimed, to "incite violence" in the city.
In London, six people were arrested as thousands marched on Westminster.
The event in London was more peaceful than recent tuition fee marches - with some of the protesters afterwards heading to join demonstrations outside the Egyptian embassy.
In Manchester, police praised the march and rally organised by the TUC, National Union of Students (NUS) and University and College Union (UCU) as "good natured, very convivial and peaceful".
But it was after speakers, including UCU leader Sally Hunt and Manchester Labour MP Tony Lloyd, finished addressing the crowd of at least 3,500 that a splinter group marched back towards the city centre.
Greater Manchester Police (GMP) said several attempts to negotiate with them were ignored and claimed their attempts to break through police lines posed a safety risk.
In a statement, Assistant Chief Constable (ACC) Neil Wain said: "It is clear this group were intent on getting into the city centre to incite violence and cause damage to people living and working in our city centre.
"Sadly on one occasion security staff at a busy shop were targeted and there were a number of minor scuffles with my officers."
The group marched along Market Street, one of Manchester's busiest shopping areas, and entered the Arndale Centre, where staff at Topshop and Vodafone put down their shutters.
A smaller group later attempted to force their way into the Next department store but were held back by security staff as police arrived on the scene.
About 100 protesters were eventually contained by police on Deansgate near to the Hilton Hotel.
"This was a necessary and proportionate response because this group were intent on committing violence and disorder, and were also running in front of traffic, putting themselves and others at risk," ACC Wain added.
"Containment was needed because clearly, there could have been a serious injury if these people continued to run in front of traffic in our busy city centre."
Throughout the day protesters used social networking websites and Twitter to organise and report on the event, with many complaining of police using so-called "kettling" tactics on the crowds.
Thirteen of those arrested - all men - were held on suspicion of section five public order offences. Six were arrested for breach of the peace and one for obstructing a public highway.