MANILA, Philippines -- Global warming may have contributed to a 43 percent rise in the number of dengue cases in the Philippines for the first half of the year, the health secretary said Wednesday.

The biggest increase in the country was seen in Metro Manila, where there was an almost 200 percent increase.

According to government figures 15,061 cases of the disease in the Philippines were reported in the first six months of the year.

"The increase in the number of dengue cases may be attributed to the constantly changing climate brought by global warming as well as congestion in urban areas," Health Secretary Francisco Duque said.

Deaths due to dengue rose to 172 compared with 115 for the first half of 2007, he said.

Metro Manila had the highest number of cases, an increase of 191 percent over the same period in 2007.

World Health Organization officials earlier this year warned climate change was increasing the incidence of dengue fever and other infectious diseases in the country.

There is no known cure or vaccine for dengue fever, which is transmitted by the white-spotted mosquito.