Two more seals with plastic flying rings stuck around their necks and two tangled in netting have been spotted by volunteers on the Norfolk coast.
David Vyse, of the Friends of Horsey Seals wildlife group, said sightings were reported in the last fortnight in the Horsey area.
The volunteers have helped to rescue three seals with their necks trapped in flying discs to date, but only after they weakened enough to be caught.
The four animals seen in the recent sightings remain in the wild.
The sightings come as the RSPCA reported the number of animals affected by plastic litter is at an all-time high.
The RSPCA recorded a rise in incidents from 473 in 2015 to 579 in 2018.
Some animals are being disproportionately affected by plastic, the charity said, with a fourfold rise in seals.
There were 28 such incidents recorded in 2018 compared with five in 2015, the RSPCA said.
Local volunteers have launched a leaflet campaign to encourage people to take home flying rings that could harm seals.
In Norfolk there have already been three reported cases of seals who got plastic flying discs stuck round their necks, which then restricted their growth and cut into their flesh.
Mrs Frisbee was rescued in 2017 and released the following year, and a second seal, called Pinkafo, was rescued last December and released in May.
A third seal was named Sir David, after Sir David Attenborough, whose Blue Planet II series raised awareness of the environmental damage caused by plastic pollution.
The disc was cut off Sir David’s neck by a vet using surgical scissors and he was released back into the wild last month after three months in the care of the RSPCA.
Microplastics from bottles and food packaging discovered in snow on sheets of ice… floating in Arctic – click here