Zardari's failure to reinstate judges deposed by Musharraf has angered thousands [AFP]

The news broke around 6:30am local time.

When I heard, I could not quite believe it.

Nawaz Sharif, former prime minister and leader of the biggest opposition party, under house arrest. All because of his support for the lawyers' protest movement and their call for sacked judges to be reinstated.

We were expecting something like this but after some last-minute negotiations between Sharif and the government, many here in Lahore believed a compromise was being reached.

'Long march'

Then, on Saturday night, Sharif held a news conference saying the "long march" would go ahead. This is said to have angered the government who then decided to place him under house arrest.

At the time of writing this I am outside the Sharif residence.

The situation is on a knife edge. Police in full riot gear standing menacingly outside the main gate of his house. His supporters demanding his freedom.

Sharif has spoken to us by phone, saying he will continue his fight.

His supporters wave their green party flags outside and chant "Long live Sharif!" and "Zardari is a dog".

The blame the Pakistani president for Sharif's current predicament.

It's another twist in a story that has more than its fair share.

This was supposed to a be great day for the lawyers' movement when they began the next stage in the "long march" that started on March 12 from cities across Pakistan.

But the government clampdown has had an effect on the marchers.

But it is not just house arrests - Lahore is a city under lockdown. Paramilitary forces race through its normally packed streets.

Sweeping steps

Pakistan's government, fearful of the anti-government march, has taken sweeping measures to stop lawyers and protesters gathering at their first stop en route to their ultimate destination: the parliament in Islamabad.

One group of lawyers decided to camp inside the court in Lahore hoping to avoid security cordons, only to be locked inside.

Still they are determined.

Behind the locked gates they chant: "We will go to Islamabad we will stage our sit in."

The quiet on the streets didn't last long. Clashes broke out between lawyers and police, and tear-gas shells were fired.

Still the lawyers are adamant that they will protest all the way to Islamabad. But with key figures under house arrest and streets blocked, it would seem their determination to march is matched only by the government's determination to stop them.