ISLAMABAD (Guardian) -- Sharif supporters attempting to reach the airport clashed with police at barricades near the airport, wire agencies reported. Hundreds of people were rounded up over the previous 24 hours including Mr. Sharif's spokesman, Ahsan Iqbal.

Mr. Sharif had been due to arrive via Muscat but changed flights at the last moment at Heathrow airport last night.
As Mr. Sharif apparently negotiated with government officials, the black-uniformed commandos moved to the front of a VIP reception area.
Mr. Sharif left London on course for a showdown with President Pervez Musharraf in a defiant bid to end his seven-year exile.
The government banned political rallies, arrested hundreds of opposition officials and declared an airport ""terror alert"" in an effort to scotch plans by Sharif supporters for a rousing welcome.
Local media reported that mobile phone-jamming devices and additional surveillance cameras had been installed in the airport.
Mr. Sharif said yesterday he was undeterred, however. ""I'm feeling great,"" he said as uniformed British police escorted him through a crowd of supporters at Heathrow airport on his way to the flight.
""My ambition is very clear: I have to take Pakistan back to the rule of democracy, because unless we have this, we will continue to be in a state of mess, as we are today,"" he told reporters on the plane as he waited for takeoff.
Earlier, he acknowledged that it might be dangerous to return. ""I know that this is a risky course and there are dangers in it for me, but I am doing this for Pakistan,"" he told Geo news from London. ""I will be happy that for a small price -- my going to jail -- Pakistan will win freedom.""
In Islamabad, Mr. Sharif's supporters planned giant rallies to converge on the airport as he arrived. ""The government's knees are shaking,"" said a spokesman, Ahsan Iqbal. ""Gen Musharraf is already defeated.""
The deputy information minister, Tariq Azim, said there were ""no special plans"" for Mr. Sharif, but hinted that he faced arrest. ""He will be allowed to land and treated like any other commercial passenger. What happens after that is up to the legal experts,"" he said.
There was a whiff of panic about government efforts to thwart Mr. Sharif, who has unexpectedly positioned himself on the frontline of efforts to oust Gen Musharraf. At the weekend police rounded up hundreds of Sharif supporters across the Punjab -- his party claimed 2,500 -- while many others disappeared into hiding.
The drama took a surprise twist on Saturday when the head of Saudi Arabia's intelligence services, Prince Muqrin bin Abdul Aziz, appeared in Rawalpindi alongside the prominent Lebanese politician Saad Hariri, urging Mr. Sharif to respect a 2000 agreement in which he promised to remain in exile for a decade. ""It is here and signed,"" said Prince Muqrin, waving a copy of the agreement before reporters.
But in London Mr. Sharif rejected that assertion and claimed that he understood the deal, under which he escaped a sentence of life imprisonment, would lapse in 2005. (The Guardian) On arrival in Islamabad, Mr Sharif planned to go by road to his political heartland in Lahore in a giant motorcade intended to further undermine Gen Musharraf.
The general has several options, none of them palatable. He could have Mr Sharif bundled on to a plane and flown to Saudi Arabia, as he did when his brother Shahbaz tried to return in 2004. But that would trigger a fresh confrontation with the supreme court, which ruled on August 23 that Mr Sharif has an ""inalienable"" right of return. The most likely course may be arrest. Last week the courts revived corruption charges against Mr Sharif and a murder accusation against his brother. But arrest would almost certainly trigger protest and violent unrest.
Gen Musharraf's greatest hope may lie with the other exiled former prime minister, Benazir Bhutto, though power-sharing talks in Dubai have stalled and Ms Bhutto says she will announce her own return date to Pakistan on Thursday.