Myanmar is denying Chinese accusations that one of its warplanes crossed China's border and dropped a bomb that killed four farmers.

A senior official in Myanmar's presidential office said Sunday his government regrets the deaths but denied that the bombing was carried out by Myanmar. He suggested it could have been the work of a group seeking to create confusion.

The official spoke on condition of anonymity because of sensitivity of the matter.

The incident occurred as the Myanmar government stepped up its fight against ethnic Chinese rebels in the country's Kokang region along China's southwestern border.

China says the bomb killed four Chinese in a sugarcane field Friday and wounded nine others. Beijing strongly protested the bombing and says it has sent fighter jets to warn off further intrusion.