North Korea's state news agency has released photos of diagrams that show what appear to be the designs of one or possibly two new missiles.

The diagrams were seen hanging on a wall behind leader Kim Jong Un during a visit to a plant that makes solid-fuel engines for the country's ballistic missile program.

One showed a missile called Pukguksong-3, which appears to be the latest in the Pukguksong, or Polaris, series. The other was harder to discern but appeared to be in the "Hwasong," or Mars, series.

The photos were released by the Korean Central News Agency on Wednesday.

The KCNA report said Kim called on workers to produce more solid-fuel rocket engines and rocket warhead tips.