A pregnant rhinoceros was slaughtered by poachers in one of the most secure parks in Africa, marking the first time in six years a rhino was killed within Nairobi National Park, officials in Kenya said.

Black market demand for rhinoceros horn -- fueled mostly by China and Vietnam -- is high, commanding a price higher than gold, which makes the poaching of rhinos in Africa a difficult problem to control.

''It shows the great heights these criminals are willing to go,'' Paul Udoto, spokesman for the Kenya Wildlife Service, said to The Associated Press. ''It's something we are taking very seriously because it's a new level of poaching for us. And it is indeed very daring.''

Last year 29 rhinos were killed by poachers in Kenya; this year the number is already at 35, the AP reported. A graphic photo of the slaughtered rhino is here.

Nairobi National Park is located only four miles from the center of the Kenyan capital city, so humans, including opportunistic poachers, are never very far away from the park's boundaries.

Kenya's penalty for poaching has not kept up with the times, which does little to deter poachers from breaking the law.

In January four Chinese men were found guilty of attempting to smuggle ivory out of Kenya -- none of them received prison time and they each paid a $400 fine, the AP reported, a sum easy to swallow when ivory can sell for $1,000 per kilogram. Rhinoceros horn can sell for even more, depending on its destination. In May, The Atlantic reported the illicit substance fetches up to $100,000 per kilogram, which makes it worth more than its weight in gold.

Penalties may soon increase, however, as the Kenya's parliament is expected to consider a motion to increase the minimum penalty for crimes against endangered or threatened species to a minimum fine of $115,000 or 15 years in prison, the AP reported.

But while a change in Kenyan law may thwart poachers in the country, the crime is still likely to continue elsewhere in Africa so long as the demand for ivory and rhino horn remains high.

Last week, officials in Hong Kong seized a cache of 1,200 polished ivory tusks, 13 black and white rhino horns and five leopard skins, all of which were reportedly smuggled out of Nigeria in shipping containers. The haul was estimated to be valued at $5.2 million.

At the end of July, officials at the same port seized more than 2 tons of ivory worth an estimated $2.2 million in a container originating from the West African nation of Togo.