Royal Mail claimed today that more than a quarter of staff members are ignoring the postal strike, as negotiations with union leaders continued.
Official payroll figures showed that 35,000 Royal Mail workers have turned up for work as usual, it reported.
"The high level of attendance means that we are continuing to process mail and that deliveries are taking place across the country, albeit at reduced levels," the Royal Mail said.
It added that attendance was as high at 90% in some locations. It also claimed 50% more people are working than on previous strikes, "showing that support for the Communication Workers Union strike amongst its members is weakening".
But the CWU, which has around 130,000 members at Royal Mail, strongly rejected claims it was losing support from its members.
"We are seeing really overwhelming support for the strike across the UK," insisted a CWU spokeswoman.
She added that the two sides are still talking today, which suggests there is still a chance that the two-day strike, which began at noon on Thursday, could be called off early.
The CWU plans to hold a second 48hour strike, starting next Monday. It has rejected a 2.5% pay offer, saying it will not accept a rise below the rate of inflation. It also fears 40,000 jobs will be axed once more automatic letter-sorting equipment is installed as part of Royal Mail's modernisation plans.
Royal Mail also said it has reached a deal in principle with the Unite union, which represents 12,000 managers, over pay, modernisation and pension reform.
The deal includes agreements to move to pensions based on career-average salaries from next year - although existing pension reserves will continue to be linked to final salaries - and raising the retirement age from 60 to 65 from 2010.
