Picket lines have been mounted outside Royal Mail delivery and sorting offices after workers launched a 48-hour strike in a worsening dispute over pay.
Members of the Communication Workers Union (CWU) walked out, which will impact deliveries of post across the country. In a statement, Royal Mail said members of the public should expect "significant disruption" to their services on strike days.
Talks between the two sides were held on Thursday but there was no sign of any progress being made and the union is planning to step up industrial action in the coming weeks. The union said the walkout by around 115,000 of its members is the biggest strike of the year, and a further 19 days of strikes have been announced on different days throughout October and November in a major escalation of the dispute.