The scandal in South Korea involving President Park Geun-hye has taken an unexpected twist with news that Viagra has been found in her offices.

Authorities found the pills - usually used to treat erectile dysfunction - while investigating corruption allegations against Ms Park.

The government says the Viagra was bought to combat altitude sickness.

The South Korean leader is accused of allowing her friend, Choi Soon-sil, to influence her decisions.

The presidential office confirmed it bought 364 Viagra and similar generic pills to deal with altitude sickness on official trips to East Africa, although the pills were never used.

The BBC's Stephen Evans in Seoul, says the discovery of Viagra will add an air of remoteness to the president. Many Koreans believe Ms Park is living in a "different world" which will exacerbate political pressure on her to resign.

Some early rumours among Koreans alleged Ms Park could have been involved with cultish rituals with her friend Ms Choi.

Ms Choi, a long-time friend of Ms Park's, is the daughter of Choi Tae-min, a shadowy quasi-religious leader who was closely linked to Ms Park's father, then-president Park Chung-hee.

Viagra and altitude sickness?

The discovery of Viagra grew out of the drug UK92480, a new treatment for angina, a heart condition that constricts the vessels that supply the heart with blood.

It failed in treating angina, but during drug trials many volunteers reported an unusual side effect - lots of erections. Scientists ran more tests and discovered its effectiveness at treating erectile dysfunction.

Because of biological similarities between the lungs and penis, scientists also discovered it could help protect against pulmonary hypertension, common in climbers.

At high altitudes decreased levels of oxygen can trigger high blood pressure in the lungs, which in extreme circumstance can be fatal.

Viagra reduces high blood pressure and improves the transport of oxygen in the blood.

Meanwhile, South Korean authorities have raided the offices of Samsung and the national pension fund as part of a corruption investigation linked to the president.

They are probing whether Ms Park pressured the fund to support a Samsung merger, said the Yonhap news agency.

Samsung's offices had already been raided over related allegations.

Wednesday's raid had to do with a merger last year between the electronics giant's construction arm, Samsung C&T, and an affiliate firm, Cheil Industries.

For weeks, tens of thousands of protesters have gathered in Seoul to demand Ms Park's resignation - a call she has resisted.