It has emerged Walter Palmer may have been hunting another big trophy kill, as the US opens a probe into the death of iconic lion Cecil in Zimbabwe.

The American dentist who hunted down the big cat wanted to kill a massive elephant after he shot Cecil, The Telegraph reported.

However, according to the guide who helped him, they were unable to locate one big enough to be hunted, while also revealing the hunt “went wrong from the beginning”.

• Hunter ‘regrets’ killing beloved Zimbabwe lion
• Rhino poaching hits record high
• Paddleboarder reels in giant Goliath fish

Theo Bronkhorst, poacher, sits with his lawyer helping him with charges over the death of the loved lion. Photo: AAP

“The client asked if we would find him an elephant larger than 63 pounds, [the weight of one tusk] which is a very large elephant,” guide and hunter Theo Bronkhorst told The Telegraph.

“I told him I would not be able to find one so big, so the client left the next day and went to Bulawayo for the night and then flew out [to Johannesburg] midday the following day.”

Mr Bronkhorst has appeared before a magistrate in Hwange and has been remanded on bail. He is forbidden from continuing his hunting business, run since 1992.

Meantime in the US, the federal Fish and Wildlife Service said it had opened a probe into the hunt.

“We’re investigating the killing of #CecilTheLion. Will go where facts lead. We ask Dr. Palmer or his rep to contact USFWS immediately,” the agency said on Twitter.

Walter Palmer killed Cecil the lion earlier this month after the big cat was allegedly lured out of the Hwange National Park boundaries.

Minnesota congresswoman, Betty McCollum, joined calls to investigate the dentist, a seasoned hunter with a poaching conviction over the 2008 killing of a black bear in the United States.

She urged the US Attorney’s Office and the USFWS to “investigate whether US laws were violated related to conspiracy, bribery of foreign officials, and the illegal hunting of a protected species or animal.”

In 2008, Mr Palmer plead guilty to federal charges of making false statements in realtion to bear hunting activity in Wisconsin.

The killer of Cecil the Lion Dr. Walter J Palmer, dentist from Minnesota, hope he pays a price, & loses his patients. pic.twitter.com/e3cqMS9CMC

— Joe (@politicallord) July 28, 2015

He was sentenced to a year of probation and a fine of $2,938.

The professional Zimbabwean hunter who organised the hunt has been charged in Zimbabwe with “failing to prevent an illegal hunt.”

But a court hearing for the landowner accused of allowing the hunt was delayed on Thursday.

But Mr Palmer remained out of the public eye, as crowds left plush toys of lions, tigers and monkeys at his River Bluff Dental practice in Minnesota.

A sign reading “Rot in Hell” was plastered on the office door.

Coinciding with the global outrage around Cecil’s death, the UN General Assembly has adopted a resolution to tackle illegal smuggling of endangered wildlife like elephants and rhinoceros.

While Thursday’s resolution – the first of its kind – is not legally binding, it reflects worldwide opposition to poaching.

– with AAP