By Zoe Nauman For Dailymail.comThey divorced just over 28 years ago, and after ironing out their differences have become friends.

But Madonna and Sean Penn have reignited rumours they may be enjoying more than just a platonic relationship after the singer stepped out at her ex husband’s side again on Saturday night.

The pair were appearing at the actor’s Help Haiti Home fundraiser, which was held at The Montage Hotel, in Beverly Hills.

And she was even joined by her children Mercy James, and David Banda at the function.

Madonna wore a sheer frock in a midnight hue, while she showcased her assets in a lace brassiere.

The Material Girl wowed the crowd with an acoustic number later in the evening – playing a small guitar she sang in French much to everyone’s delight.

Madonna remained coy when asked why she was at the event telling E! News the only reason was ‘Haiti.’

Rumours have been circulating she may be more than just friendly with her ex since last Autumn.

And in December she came to his defence when Sean was involved in a defamation lawsuit against Lee Daniels, saying that he never physically abused her during their two year marriage.

The singer, who split from the actor in December 1987, stated in court documents filed in New York State Supreme Court: ‘While we certainly had more than one heated argument during our marriage, Sean has never struck me, ‘tied me up,’ or physically assaulted me, and any report to the contrary is completely outrageous, malicious, reckless and false.’

Later in the evening Madonna took to Instagram and posted a snap from the event.

She was seen with Sean and another pal.

The singer captioned the shot: ‘Tonight was Fire! Thanks to Sean and everyone at J/PHRO!!!! We raised 6 million dollars for Haiti.’

Meanwhile the actor, who appeared cool and calm at the event, may have to have dealings with the law again.

Sean is under investigation after finding the world’s most wanted drug lord, while the whole of Mexico’s crime fighting elite were looking for him.

The actor has got into a lot of hot water for interviewing El Chapo when he was one of Mexico’s most wanted after his jail break last year.

He unwittingly led the Mexican authorities to the cartel boss after meeting him – and is now under investigation.

El Chapo admitted in the bizarre interview to being the biggest drug trafficker in the world and said he sent engineers to Germany to learn how to build the tunnel he would eventually use to escape a maximum security prison.

The cartel boss was captured on Friday in a daring 4am raid by Mexican marines and was returned to Altiplano jail.

The double Oscar-winning actor’s meeting with El Chapo led to the gun battle in which he was captured, an official said.

However, if he was concerned about any possible trouble he could be in, the actor did not show it on Saturday evening.

The fifth year of his fundraiser – Help Haiti Home, he smiled for photographers and looked dapper in a black suit and tie, teamed with a navy shirt.

The actor who did the chat for Rolling Stone, said he did not turn El Chapo in because the drug lord’s trust ‘was not to be f***ed with’.

‘I take no pride in keeping secrets that may be perceived as protecting criminals, nor do I have any gloating arrogance at posing for selfies with unknowing security men. But I’m in my rhythm.

‘Everything I say to everyone must be true,’ Penn wrote.

El Chapo – whose real name is Joaquin Guzman, was caught after contacting actors and directors about making a Narcos-style biopic about his life, Mexican officials said.