The cancer-stricken wife of Pakistan's jailed former prime minister Nawaz Sharif died in London on Tuesday while her husband and daughter were in prison, officials said.

Kulsoom Nawaz Sharif, 68, died after months in a coma. She was diagnosed with lymphoma last year, barely a month after Nawaz Sharif was removed from office by the Pakistan Supreme Court, which ordered him to face trial in an anti-corruption court.

"The wife of Mian Nawaz Sharif is no more among us. May God rest her in peace," Shehbaz Sharif, the former prime minister's brother, said on Twitter.

New Prime Minister Imran Khan issued a statement offering condolences, and said the government "as per law" would provide assistance to the family.

"She was a courageous woman of great dignity and confronted her disease with fortitude," Khan said on Twitter.

It was not immediately clear whether Nawaz Sharif or his daughter, Maryam, might be released from prison to attend funeral services.

Nawaz Sharif was in London with Kulsoom earlier this year when the anti-corruption court handed him a 10-year jail term and sentenced his presumed political heir, Maryam, to seven years in prison over the purchase of luxury flats in London in the 1990s.

The father and daughter left her bedside to return to Pakistan to rally their followers ahead of July 25 elections, which their party lost to the former cricket star Imran Khan's party. Both were arrested on arrival and have been imprisoned since.

Kulsoom Sharif was briefly a member of parliament after she won her husband's former seat in a by-election after the Supreme Court disqualified him.

Three-time-premier Nawaz Sharif, who was removed from office in each of his elected terms, has maintained that his most recent ouster in July 2017 and subsequent conviction were part of a plot against him by the powerful military and the judiciary.

The army has repeatedly denied any interference in politics, while the courts insist justice is carried out impartially.

Army chief General Qamar Javed Bajwa expressed "grief and heartfelt condolences to the bereaved family", said the official military spokesman.

Up until her husband's ouster last year, Kulsoom Sharif had never been a politician, but she memorably led protests after the 1999 military coup that ended a previous Sharif administration.

With her husband jailed by General Pervez Musharraf, she broke through a police barricade set up around her home in Lahore in July 2000 in an attempt to prevent her from leading a public rally.

She managed to get away in a car, which was chased by the police for several miles. When police finally surrounded the car, she locked herself in for several hours in a standoff until police finally towed the vehicle away.

The Musharraf regime eventually allowed Nawaz and Kulsoom Sharif to leave the country, and they spent years in exile until returning in 2007 to contest new elections after Musharraf stepped down in the face of mass protests.

(Writing by Kay Johnson; Editing by Nick Macfie)