Nature of force between two permanent magnets When we put two permanent magnets close to each other they repel or attract each other and this process increase their kinetic energy. I know that magnetic force can't increase kinetic energy so plz explain which type of force is this.
 A: 
I know that magnetic force can't increase kinetic energy so plz explain which type of force is this.

Assuming you meant potential energy when you said, "kinetic energy."
If two magnets are oriented so that they repel each other, then you increase the potential energy of that system when you push them closer together. Conversely, if they are oriented so that they attract each other, then once again, it is you who increases the potential energy of the system when you pull them apart.
A: 
When we put two permanent magnets close to each other they repel or
attract each other and this process increase their kinetic energy

If you have two magnets with like poles (north or south) facing each other you have to do work against the repulsive force to push them closer together. That work increases the potential energy between the magnets. If you then let the magnets go, they will fly apart due to work done by the magnetic field, gaining kinetic energy.
Likewise, if you have two magnets with opposite poles facing each other you have to do work to pull them apart against the attraction forces. If you then let the magnets go, they will fly towards each other due to the work done by the magnetic field, gaining kinetic energy.
The second example is equivalent to lifting an object off the ground and then releasing it. The work you do in lifting the object increasing the potential energy between the object and the earth is converted to kinetic energy when released due to the work done by gravity.

I know that magnetic force can't increase kinetic energy so plz
explain which type of force is this.

The magnetic force can give the magnets kinetic energy as described above. The key point is the kinetic energy of the magnets equals the energy you supplied doing work to push them together or pull them apart (ignoring energy dissipative effects like friction and air resistance) increasing their potential energy.
As a final comment, the ability of the magnets to store potential energy will degrade over time. The magnetic field of a magnetic was created by causing the atoms of the iron to line up when placed in a strong magnetic field. But over time, at any temperature above absolute zero, the atoms will move around and randomize their positions causing the magnet field to slowly weaken. The process can be sped up by heating or dropping the magnet.
Hope this helps.
A: "I know that magnetic force can't increase kinetic energy"
That statement applies to the magnetic force on a charged particle.
The magnetic forces on magnetic moments, which are lined up in a magnet, do produce kinetic energy, which will push the magnets apart or attract them.
