The accident occurred near the city of Klagenfurt
Austrian far-right politician Joerg Haider was drunk at the time of his fatal car crash last Saturday, an official from his party has said.
Stefan Petzner, the new head of Mr Haider's Alliance for Austria's Future (BZO), said the blood alcohol level was well above the legal limit.
Mr Haider, 58, was driving alone after leaving a nightclub early on Saturday when his car crashed and overturned.
Police have said he was travelling at 142km/h (88mph) in a 70km/h zone.
The accident occurred south of Klagenfurt, the capital of Carinthia, where he was the provincial governor.
"It is correct that... Joerg Haider was under the influence of alcohol at the time of the accident. I can and must confirm that," said Mr Petzner.
He said he had made the announcement because of widespread rumours that Mr Haider had been driving drunk.
Mr Haider had been at a nightclub before his crash
Mr Haider's car overturned a number of times, causing him serious head, chest and spinal injuries. He died on the way to hospital.
Mr Haider had reportedly been due to attend his mother's 90th birthday celebrations later in the day.
Mr Haider was known for his anti-immigration and anti-EU policies.
The BZO was one of two right-wing parties that did better than expected in general elections last month, fuelling speculation of a possible role in a ruling coalition.
His deputy, Mr Petzner, took over as head of the BZO after Mr Haider's death.
Mr Haider was first elected as governor of Carinthia in 1989. He was forced to resign in 1991 after he made comments praising the employment policies of Nazi Germany.
He was re-elected governor in 1999 and 2003.