Mughal, also director of an interfaith national hate crime reporting project, Faith Matters, said he had observed that people are scared, particularly female Muslims who wear headscarves and have told Tell Mama that they are afraid to go out. "It's quite endemic," he said.
Tell Mama recorded 632 incidents of anti-Muslim abuse in the year from March 2012, it said, about three-quarters of which occurred online. More than half were directed at women.
Imams sign letter condemning attack
The apparent increase in abuse comes as Muslim leaders, as well as their Christian counterparts, seek to keep communities calm.
Shaykh Shams Adduha, founder and director of Ebrahim College, which teaches Islamic studies in London, is one of nearly 100 imams and Muslim groups to have signed a letter Friday condemning the "outrageous attack" on Rigby and offering their condolences to his family.
"We share the absolute horror felt by the rest of British society at the sick and barbaric crime that was committed in the name of our religion. We condemn this heinous atrocity in the strongest possible terms. It is a senseless act of pure depravity worthy of nothing but contempt," it read.
Shams Adduha told CNN Saturday that the Muslim community had reacted promptly and was working hard to defuse tensions.
"First of all we've been very open in our condemnation and very open about the fact that there is no place ... in Islam for this kind of act," the imam said.
"At the same time we've been calling for calm, we've constantly been talking to our communities to make sure that their fears are allayed. But of course the reactions are happening -- and they will happen."
These types of attacks are also a reaction, he said, to problems and grievances among "angry young people out there in the world."
With regards to the Woolwich attack, he said, Muslim leaders must make clear that what happened is "un-Islamic" and seek to educate young people so they are not susceptible to "fringe voices."
Prime Minister David Cameron stressed Thursday that "the fault lies solely with sickening individuals who carried out this attack," adding that "nothing in Islam ... justifies this truly dreadful act."
'Eye for an eye'
One of the attack suspects apparently approached a man filming the gory scene in the Woolwich neighborhood and suggested that Rigby had been targeted only "because Muslims are dying daily" at the hands of British troops like him.
"We must fight them as they fight us. An eye for an eye and a tooth for a tooth," he said in the video aired by CNN affiliate ITN.
Britain's armed forces have served in Iraq and Afghanistan. All its combat troops are due to leave Afghanistan by the end of 2014.
The identity of a second man, aged 22, seized at the scene by armed police has not been released. Both suspects were shot and remain in hospital.
A third man, aged 29, who was arrested on suspicion of conspiracy to murder on Thursday is also still in custody.
Donations flood in
It is understood that the two individuals suspected of carrying out the knife and cleaver attack were known to Britain's domestic security service. They had featured in previous investigations into other individuals, but were not themselves under surveillance.
CNN understands that one line of inquiry being examined in the Woolwich terror investigation is that suspect Adebolajo might have attempted -- but failed -- to travel to Somalia some time last year.
The brutal slaying of Rigby near the Royal Artillery Barracks in Woolwich, a working-class, multicultural neighborhood, shocked people across the United Kingdom.
The 25-year-old, who was married and had a 2-year-old son, was a machine gunner who became a recruiter. He was also a ceremonial military drummer.
His family spoke Friday of their sorrow at losing a son, husband and brother who was dedicated to his job and devoted to his family.
Help for Heroes, a charity which helps injured military veterans and servicemen and women, said Saturday that nearly £600,000 ($907,590) in public donations had poured in since the news of Rigby's murder -- with more still coming in.