Washington, Oct 10 (DPA) Democratic presidential candidate Barack Obama is buying up rare 30-minute advertising slots on network television shortly before the general election, according to media reports. The ads would run Oct 29, six days before the election, at 8:30 p.m. on the US East coast - considered a prime-time slot - and 5:30 p.m. in the West.

A deal has already been done with CBS and the campaign was still working out the details with NBC and Fox, Politico.com reported Thursday.

Republican rival John McCain meanwhile stepped up his attacks with less than one month to go, releasing the first ad directly tying Omaba to Bill Ayers, a member of a radical 1960s anti-Vietnam war group.

“Barack Obama and domestic terrorist Bill Ayers. Friends. They’ve worked together for years,” says a narrator in the web ad, calling Obama “too risky for America”.

McCain’s vice presidential candidate Sarah Palin launched the first salvo last week, accusing Obama of “palling around with terrorists” during a campaign rally.

Ayers in 1969 helped found the radical group known as the Weather Underground, which attacked federal buildings in Washington to protest the Vietnam War. The attacks did not result in any deaths. Ayers, who escaped conviction, is now a professor at the University of Illinois in Chicago.

Ayers is an influential figure in some Chicago political circles. Obama’s campaign said the two are not friends and derided the personal attacks as designed to detract from real issues like the economic crisis.

“Its now clear that John McCain would rather launch angry, personal attacks than talk about the economy,” Obama spokesman Tommy Vietor said in a statement.

But Obama has also fired back, regularly slamming McCain for being “out of touch” and reviving the Arizona senator’s role in the savings and loans scandal of the late 1980s and early 1990s.