The number of children killed and injured in Afghanistan's war has risen sharply this year, the U.N. Children's Fund, said, calling the trend "unacceptable" and "very worrying."

At least 414 children were killed or injured in the first four months of this year, up 27 percent over the same period the previous year, UNICEF said.

Of those, 121 children were killed and 293 were injured through April 30, UNICEF said in figures released Thursday. Roadside bombs and suicide attacks accounted for the largest number of casualties — 37 percent — and the U.N. has particularly criticized the Taliban's use of indiscriminate weapons triggered by victims' stepping on or driving over a pressure plate as a possible war crime.