Twitter Inc is offering advertisers incentives to increase their spending on the platform, according to an email sent on Thursday to advertising agencies, an effort to jump-start its business after Elon Musk's takeover prompted many companies to pull back.

Details of the incentive offer were first reported by newsletter Marketing Brew.

Twitter billed the offer as the "biggest advertiser incentive ever on Twitter," according to the email reviewed by Reuters. U.S. advertisers who book $500,000 in incremental spending will qualify to have their spending matched with a "100% value add," up to a $1 million cap, the email said.

Musk's first month as Twitter's owner has included a slashing of staff including employees who work on content moderation and incidents of spammers impersonating major public companies, which has spooked the advertising industry.

Many companies from General Mills Inc to luxury automaker Audi of America stopped or paused advertising on Twitter since the acquisition, and Musk said in November that the company had seen a "massive" drop in revenue.

Ad sales account for about 90% of Twitter's revenue.

Twitter did not immediately respond to a Reuters request for comment.

Advertisers in Britain and Japan who book $250,000 in incremental spending would receive a 100% match, while brands in all other regions that spend $50,000 would receive the match, according to the email.

Earlier in October, Musk said he wanted Twitter to be "the most respected advertising platform" and not a "free-for-all hellscape", in a bid to gain the trust of ad buyers ahead of the close of his deal.