Just 4,300 of the 13,000 Sandd workers have signed up to work for PostNL ahead of the February 1 merger.

PostNL offered all 11,000 Sandd delivery workers are job, but 40% rejected the offer outright. Of those who said they were interested, 4,000 signed up to deliver mail for PostNL. A further 300 Sandd workers, including drivers and sorters, have also moved to the former state monopoly.

In particular, Sandd workers are unhappy at being asked to deliver post on more days than just Tuesday and Friday, and Saturday, when PostNL does deliver, is also a major issue, NOS said.

PostNL and Sandd agreed to merge last year, and the takeover was initially rejected by the Dutch competition authority, but later approved by the economic affairs ministry.

The merger creates a single postal delivery system once again, after 20 years of competition.

PostNL currently controls some 70% of the Dutch postal market and Sandd, which was founded in 1999, controls virtually all the rest – primarily business deliveries.