* Regulators say first report showed improved competition
* Google could face bigger fine if it fails to comply
* Rivals say still no level playing field
By Foo Yun Chee
BRUSSELS, Oct 1 (Reuters) - Google has provided a second report detailing the effects of its proposal to allow more price comparison rivals to bid for ads on top of its search page, EU antitrust regulators said on Monday.
Alphabet unit Google came up with the offer after being hit by a fine for 2.4 billion euros ($2.79 billion) in June for using its search engine market power to boost its own comparison shopping service. It is required to provide periodic reports on the proposal.
The European Commission in June said competition was improving after the world's most popular internet presented a first report which showed more competition for ads at the top of a search page.
Rivals however have disputed its claim of creating a level playing field and want more regulatory action.
Antitrust enforcers could slap fines of up to 5 percent of Google's average daily worldwide turnover for failing to comply with its order but have not indicated they would take further action.
"We have received the second Google shopping report," the Commission said, without providing details.
Google did not immediately respond to a request for comment.
$1 = 0.8616 euros Reporting by Foo Yun Chee Editing by Edmund Blair