They were found inside a newly-discovered well at a sacred site in Saqqara, south of the capital, Cairo.
Thirteen coffins were discovered earlier this month, but a further 14 have followed, officials say.
The discovery is now said by experts to be one of the largest of its kind.
Images released show colourfully painted well-preserved wooden coffins and other smaller artefacts.
Saqqara was an active burial ground for more than 3,000 years and is a designated Unesco World Heritage Site.