A lightning strike at a primary school in western Uganda killed 19 students and injured 50, Ugandan police said on Wednesday.

Lightning on Tuesday hit Runyanya primary school in Kiryandongo district, about 225 kilometres (135 miles) northwest of Kampala, killing 18 children outright with a further child dying from burns on Wednesday, police spokeswoman Judith Nabakooba told AFP.

"The injured were taken to hospital nearby and 15 of those who were seriously injured were transferred to Mulago hospital," in Kampala, Nabakooba said.

Local media reported that a further 21 pupils were burned Tuesday after lightning struck at a second school in Zombo district, around 380 kilometres north of Kampala. Police could not confirm the incident.

Charles Basalirwa, head of the meteorological unit at Kampala?s Makerere University, told AFP that although Uganda has seen deadly lightning strikes in the past the frequency has increased dramatically.

"In Uganda we have had these events and these strikes before but never as severely as we have seen over the past few weeks," Basalirwa said.

He said the sharp increase in the number and strength of lightning strikes was one more sign, along with increased droughts and flooding, of the extreme weather conditions being caused by climate change in the region.

Although he said it was still too early to tell whether these conditions were becoming normal, Basalirwa urged the Uganda government to put in place measures to deal with weather extremes, such as building more lightning rods.

"It is now more and more urgent that we address these issues...unfortunately our officials have not taken these matters as seriously as they need to," he said.

Nabakooba said the children killed in Kiryandongo had been sheltering from the rain in the school as they waited to go home when the lightning struck.

She could not provide an exact figure for the total number killed countrywide by lightning in recent weeks, but local newspaper The Daily Monitor reported Wednesday a total of 28 killed and scores injured in the past week, including Tuesday's incidents.

Uganda is experiencing unseasonably heavy rainstorms and concern about the number of recent lightning strikes has prompted lawmakers to demand an official explanation from government.

Topher Mugumya, advocacy manager with Save the Children in Uganda, called for "awareness campaigns" to "make sure people have the material to put conductors on their homes," and said the government should support such measures as the rate of deaths from lightning was "alarming."

He also called for reforestation in areas that have been cleared of trees, including Kiryandongo.