Well... if you want to run both in a single gel, then go for 2%. 

2-3% use 3% for clear identification of smaller band. Note: Use the higher concentration of DNA for digestion.

Addionately to higher percentage gel you can also use special agarose which seperate low bp/small DNa fragments. Good luck!

2% agarose would be better for your gel run. you can easy visualize the difference of 400bp DNA fragment  in 2% agarose gel. 

For 100 - 500 bp , 2-3% agarose gel is enough . 

Hey  Jain

Look for PDF attached PLZ

Good luck

2% agarose gel will be perfect to separate both the bands on one gel in single run. 

In our lab we use to do 2.5% agarose gel to separate smaller fragments.

Agarose gel of 2.5 - 3 % can be used to separate smaller fragments.

I has used 2% of agarose gel