Prince Albert II has sparked further rumours about troubles in his marriage with Princess Charlene after pictures from the Red Cross Ball earlier this year revealed that his former mistress and love child were also in attendance.

Princess Charlene hasn't been in Monaco since she visited South Africa in mid-March for a conservation trip, as she contracted an ear, nose, and throat infection that required "multiple, complicated procedures" and barred her from travelling. Her husband recently visited her in the country with their two children- six-year-old twins Prince Jacques and Princess Gabriella, where they posed for several family pictures including one of the seemingly happy couple embracing each other.

The royals, who have been married for a decade, subdued the rumours with their photoshoot, but reignited them after the resurfaced pictures from the Red Cross Ball. The photographs show that at the charity event, held on July 16, Albert was accompanied by his former lover Nicole Coste and their love child Alexandre Grimaldi-Coste, reports Mail Online.

Coste was a flight attendant on an Air France plane en route from the French Riviera to Paris in July 1997 when she met the Monegasque royal, who was a passenger on the plane and asked for her phone number. They subsequently started a relationship that continued for several years, until allegedly Albert's father, Prince Rainier III, demanded that he end the affair.

Coste told Paris Match that she became pregnant with the royal's child only after a visit to celebrate her 31st birthday in December 2002 turned into a tryst. Albert provided for and visited mother and child, promising to legally acknowledge his son after a DNA test confirmed his paternity. When he did not do so, Coste offered the interview and photographs to the media.

The royal finally acknowledged the paternity of the child in a statement issued by his attorney, Thierry Lacoste, on 6 July 2005. In an April 2014 interview, Nicole Coste revealed that she had legally changed her son's surname to Grimaldi-Coste, adding the dynastic name used by the princely family.

Albert has admitted to fathering another child, a daughter named Jazmin Grace Grimaldi born through his relationship with Tamara Rotolo. The 29-year-old is the eldest child of the monarch, but not in the line of succession because her parents never married.

Albert faced a fresh paternity suit earlier this year over a love child born in the early days of his relationship with Princess Charlene, which is the root cause behind the speculations about their marriage falling apart. However, the former Olympic swimmer has maintained that she will support her husband despite the case against him.

Princess Charlene of Monaco and Prince Albert II