CAPE TOWN (Reuters) - Flying in a helicopter and armed with tranquillizer guns, South African game rangers are intensifying the search for a young lion that escaped from a wildlife park last week, officials said on Thursday.

The three-year old lion, believed to have escaped on June 5 through a hole under the perimeter fence at the Karoo National Park, was discovered missing after farmers reported tracks on their private property.

"We are still looking, but with a master tracker on board since yesterday we believe we are getting closer," said Karoo Park spokeswoman Fayroush Ludick.

When it is found, Ludick said the lion would likely be shot with a tranquillizer dart and transported back to the wildlife park it escaped from. Rangers earlier failed to lure the animal with an antelope carcass.

Situated about halfway between Cape Town and Johannesburg, the Karoo National Park is a hilly region of grassy scrubland and winding river valleys, making tracking challenging.

Two weeks ago, an American tourist was mauled to death when a lioness attacked her through the open window of a car while driving in the Kruger National Park, South Africa's biggest safari park.

(Reporting by Wendell Roelf; Editing by Joe Brock)