Madonna has been visiting her ex-husband Sean Penn's aid projects in Haiti.

The 'Hung Up' hitmaker has taken her 13-year-old son Rocco - whose father is her former spouse Guy Ritchie - with her on the trip to tour the country, which was left devastated by an earthquake three years ago and is looking at the work done by the Haitian Relief Organisation, which is run by the 'Milk' star.

Sean - who is an ambassador-at-large for Haiti - said Madonna had arrived ''a couple of days ago'' after he invited her to visit several times and he is hopeful her trip will raise awareness of the situation in the disaster-stricken nation.

He said: ''She's here, she's seeing, she's made the effort to come here, and I'm thrilled by that ... She has a unique platform, and wherever she chooses to bring that to, it's very well.''

While it is unclear how long she plans to stay, Madonna - who was married to has been very busy on her visit, which she is documenting on photo-sharing website Instagram.

In one photo, she poses with a group, including her son, at the new hospital built by public health pioneer Dr. Paul Farmer and has captioned the image ''In the magnificent hospital Paul Farmer has built in Mirebalais! Revolution of Love in Haiti''

Another picture shows her mud-spattered shoes and another features Rocco, shot from behind, with a group of local children.

It is captioned: ''Rocco swaggin it with his homey's in Cite Soleil!''

Madonna - who also has daughter Lourdes, 17, with ex-boyfriend Carlos Leon, and adopted kids David and Mercy, both eight - married Sean in 1985 and, after a tumultuous four years together, they divorced in 1989.