"Refugees are welcome" dozens of protesters chanted in England's port city of Dover on Saturday, a message intended to challenge a rival rally that was held hours later on the same streets.
Those rivals are upset that increasing numbers of migrants and refugees are reaching England from France.
Over 1,450 people crossed the channel by boat in August. The figure for this year so far is more than 5,600.
It has increased tensions between London and Paris, with Britain's right-wing Conservative government publicly pressuring France to do more to stop the crossings.
But Channel Threat Commander Dan O'Mahoney, a senior official appointed to tackle the problem, told the UK's parliament on Thursday that France has stopped 3,000 people crossing this year and was "delivering results."
Prime Minister Boris Johnson's spokesman had said on Tuesday that the increase in crossings was "unacceptable."
He blamed criminal gangs for exploiting the desperate and the vulnerable for money.