At least 24 people have been killed in a double suicide bombing in Lahore today as the Australia cricket team postponed their tour of Pakistan because of security fears.

Today’s attacks, in the heart of the country’s second biggest city, targeted offices of a counter-terrorism unit and an advertising agency.

The campaign of suicide attacks in the country, which intensified after troops stormed a radical mosque in Islamabad in July, has now claimed more than 500 lives this year.

As the bombings were taking place, Cricket Australia announced that the team would not be travelling for a scheduled three Test series, which was due to start on March 29, after taking government security advice.

The first blast hit the eight-storey headquarters of the Federal Investigation Agency (FIA) in the heart of Lahore, which also houses the offices of Pakistan's US-trained special counter terrorism investigation unit.

Police said the bomber rammed an explosive-packed vehicle into the agency's parking lot during morning rush hour, demolishing a part of the building. The explosion left at least 21 people dead and more than 100 wounded.

Minutes later, another car bomber hit an advertising agency located in a two-storey house in an upscale neighbourhood of the city, killing four people, including two children. The building was blown apart, leaving several members of staff seriously injured. Scores of nearby houses were severely damaged.

Rizwan Baseer, the head of the provincial government’s rescue agency, said 18 people had been killed in the FIA blast, in addition to the bombers.

The explosions came within a week of a suspected Islamist militant attack at Naval War College in the country’s second biggest city, which has become the main target of terrorist attacks in recent weeks.

Pakistan has been battling Islamist militancy since joining the United States-led campaign against terrorism after the September 11 attacks. While much of the violence has taken place in remote northwestern regions, suicide attacks have taken place in all of Pakistan’s major cities over the past year.

Earlier today, James Sutherland, chief executive of Cricket Australia, said: "Ultimately the starting point is to look at the Federal Government’s advice to Australian travellers to Pakistan and it’s not favourable. The question for us was to then have a closer look and say what are the implications for the Australian cricket team given those quite serious warnings that are in place on the DFAT (Department of Foreign Affairs and Trade) website."

The Australian players, particularly all-rounder Andrew Symonds, had expressed their concerns about going to Pakistan but Mr Sutherland said this was not a factor in Australia postponing the tour.

Cricket Australia told the Pakistan Cricket Board (PCB) they were willing to play the series in a third country. But the PCB instead agreed to postpone the series in the hope it could be re-scheduled in Pakistan at a later date following a week of deliberations.

Australia have not toured Pakistan since 1998 with the three-Test series in 2002 staged at neutral venues in Colombo in Sri Lanka and Sharjah in the United Arab Emirates.

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