Former US President Donald Trump said goodbye to his late first wife Ivana at a funeral service.

The 76-year-old was joined at the ceremony at New York's St. Vincent Ferrer Church on Wednesday by his wife Melania and their three oldest children, Donald Jr., Ivanka and Eric, whose mother was Ivana.

The ex-president entered the heavily secured church through a side entrance, as reported by a photographer from the AFP news agency.

According to the New York Post, Eric Trump praised his mother, who died last Thursday at the age of 73, as "the embodiment of the American dream" and as a "force of nature".

Ivanka Trump described her mother as a "pioneer".

Ivana Trump, who was born in the former Czechoslovakia, died in her Manhattan apartment last Thursday.

According to the coroner's office, she had suffered "torso injuries from an impact".

According to media reports, she may have fallen down a flight of stairs.

The former model married real estate entrepreneur Trump in 1977.

In the same year she gave birth to her first child, Donald Jr., followed by Ivanka in 1981 and Eric in 1984.

During her marriage to Trump, Ivana also held senior positions in his company.

In the '80s, Donald and Ivana Trump were among New York's most dazzling celebrity couples.

In the early 1990s, Ivana divorced the real estate entrepreneur after Trump's affair with actress Marla Maples became public.

Ivana is said to have received $20 million as a settlement.

She also built her own business by designing clothes, jewelery and beauty products and wrote several books.