Three-time prime minister Nawaz Sharif arrived back in Pakistan on Saturday after four years of self-imposed exile, primed to make a political comeback ahead of elections.

Sharif spent the past several days in Dubai and left on a chartered flight packed with journalists, touching down in the capital Islamabad around 1:30 pm (0830 GMT) according to local media.

"We are completely ready for elections," he told reporters before his flight took off.

"Our country which should have been at the heights of prosperity has really gone backwards," he said. "How did we get here? Why did it come to this?"

Sharif will travel onwards to the eastern megacity of Lahore, where supporters were already gathering for a welcome home rally with streets shrouded in green and yellow party banners, posters and flags.

More than 7,000 policemen have been enlisted to control crowds expected at the Greater Iqbal Park where his homecoming speech is due later, according to a senior officer on site.

Large banners of Nawaz Sharif at a park ahead of his arrival in Lahore. AFP

"I'm here to welcome my leader. The inflation is very high and poor people are desperate," said 18-year-old Razi Ullah. "God has given him a chance to come back and turn things around. He's done it before."

'Man of the soil'

Sharif's return has been touted for months by his Pakistan Muslim League-Nawaz (PML-N) party, whose leaders hope Sharif's political clout and "man of the soil" swagger will revive its popularity flagging amid an economic backslide.

"I am a poor man, I expect only one thing from Nawaz Sharif: that he brings down inflation," said 50-year-old Umar Sabir who travelled over 250 kilometres (155 miles) to attend the rally.

Fans call him "the Lion of Punjab", the eastern and most populous province where his support is strongest, and he is known to parade big cats at extravagant political events drumming up support.

But he faces the tough task of winning over an electorate weary of dynastic politics and a young population that has been captured by Khan's social-media-savvy party.

"Sharif's key challenge is first to establish himself and his party as viable options to replace Imran Khan, who is already popular, and secondly to turn around the economy," said political analyst Ayesha Siddiqa.

Pakistan is currently being led by a caretaker government in the runup to elections.

Agence France-Presse