By Greg Roumeliotis and Arno Schuetze

NEW YORK/FRANKFURT (Reuters) - Bayer AG <BAYGn.DE>, the German chemicals and healthcare company trying to acquire Monsanto Co <MON.N>, is exploring a sale of its radiology supplies unit that could be worth more than $3 billion, according to people familiar with the matter.

Bayer has said it does not need to sell assets to finance its $62 billion bid for Monsanto but has stressed that the strategic reviews of its businesses would continue as usual.

The company is in talks with investment banks about hiring a financial adviser to explore strategic alternatives for the radiology supplies business, including a sale, the sources said this week. Bayer may decide to keep the unit, the sources added.

The sources requested anonymity because the deliberations are confidential. Bayer declined to comment.

The radiology business generates more than 1.5 billion euros ($1.7 billion) in revenue from contrast agents and related injection equipment.

Its main products are Ultravist for computer tomography scans, with 318 million euros in sales in 2015, and Gadovist for magnetic resonance imaging scans, with 290 million euros.

Bayer has been taking steps to narrow the focus of its healthcare division to prescription drugs and consumer care products.

In 2014, it sold a unit making vascular catheters to treat clogged blood vessels to Boston Scientific Corp <BSX.N> for $415 million, followed by the sale of a blood glucose meter business to Panasonic Healthcare Holdings for 1.02 billion euros last year.

Bayer Chief Executive Officer Werner Baumann said last month that the company would continue to develop its healthcare arm, which includes stroke prevention pill Xarelto and aspirin, the painkiller it invented more than a century ago.

Monsanto turned down Bayer's $122-per-share cash offer on May 24 but said it was open to continuing discussions.

Since then, negotiations between the two companies have been at an impasse, as Bayer has refused to raise its offer without Monsanto first opening its books, sources have said. Monsanto has been holding out for an improved offer before providing confidential information to Bayer.

(Reporting by Greg Roumeliotis in New York and Arno Schuetze in Frankfurt; Additional reporting by Carl O'Donnell in New York and Alexander Huebner, Patricia Weiss and Ludwig Burger in Frankfurt; EDiting by Steve Orlofsky and Lisa Von Ahn)