Underscoring the unease, a referee caught up in Tuesday's attack alleged that police abandoned him like a "sitting duck," and video showed the gunmen sauntering down a deserted side street, apparently leaving with no fear of pursuit.

Several Pakistani officials rejected the allegation on Wednesday by British match official Chris Broad, noting that six policemen guarding the convoy were killed when it was attacked by up to 14 heavily armed men near a stadium in the heart of Lahore. One official, however, acknowledged to a local news channel security lapses including a dearth of police reinforcements.

The government had pledged to give the Sri Lankan players and match officials the same level of protection afforded a ‘Heads of State’, so the incident triggered questions about Pakistan's ability to prevent terrorist attacks.

"It is a source of embarrassment at the international level," said Ahsan Iqbal, an opposition legislator, said. "This government should be ashamed and make those responsible for criminal negligence in their duties accountable."

The lapse was all the more shocking because Pakistan knew any incident would end, perhaps for years, its hopes of regularly hosting international sporting events. Even before Tuesday's ambush, most teams chose not to visit this cricket-obsessed country because of rising violence by extremists.

Police gave conflicting accounts of the investigation. One top police official said several suspects had been taken into custody in connection with the attack. Hours later, however, another denied anyone had been detained or even questioned.

Pakistan has a web of extremist networks, some with links to al-Qaeda and the Taliban, that have attacked foreign civilians in a bid to destabilise the government and punish it for supporting the US-led invasion of Afghanistan.

Chris Broad, the match referee for the Sri Lanka-Pak series, was travelling in a van in the same convoy as the Sri Lankan team bus when the attackers opened fire with automatic weapons, grenades and at least one rocket launcher, killing his driver and critically wounding a fellow official.

"There was not a sign of a policeman anywhere," Broad said on Wednesday after flying back to Britain. "They had clearly left the scene and left us to be sitting ducks."

He did not say how he managed to escape.

Other witnesses described police trading fire with the gunmen for about 15 minutes, but at least one of the Sri Lankan players said the attackers appeared to fire at will at the bus.

"They were not under pressure... nobody was firing at them," team captain Mahela Jayawardene said after returning to Sri Lanka.

Seven players and an assistant coach on the bus were wounded, though none suffered life-threatening injuries. Players said their bus stopped for around 90 seconds while under attack, before the driver stepped on the gas and drove them to the safety of the stadium.

Broad and the players said Pakistani officials had promised to give them "Presidential-style" security as part of efforts to convince them to make the trip.

"I am extremely angry we were promised high-level security and in our hour of need that security vanished and we were left just open to anything," Broad said.

Several Pakistani officials denied that, as did the country's top cricket official.

"How can Chris Broad say this when six policemen were killed?" asked Pakistan Cricket Board chief Ijaz Butt. He declined further comment, saying he wanted to speak with Broad first.

Pressed by local media, Lahore commissioner Khusro Pervez admitted "very vivid and very clear" security lapses.

"The gunmen were meant to be combated by back-up police support which didn't arrive," Dawn newspaper quoted him as saying to a news show owned by the same media company. "All convoys are provided outer cordons, but in this case the outer cordon did not respond or it was not enough. The vehicles used for escorting the Sri Lankan convoy were not adequate."

The convoy transporting the Sri Lankan team and cricket officials was surrounded by police vehicles at the front, rear and side, and took the same route each day of the five-day test match against Pakistan's national team, authorities said. It was not clear how many police officers were in the convoy.

Players recounted their ordeal after getting home early Wednesday.

"We were just hearing bullet after bullet thump into the bus. We were hearing gunshots, a few explosions and you could see bullets sometimes hitting a seat," Kumar Sangakkara said.

Jayawardene, the team captain, said it "was just a constant barrage of bullets. We don't know which direction it was coming from. It was just all over."

The team didn't panic, even when the bullets began finding their mark, coach Trevor Bayliss said.

"Everything was very calm and very quiet, and every now and then someone would say, 'I'm hit,' and then someone else said, 'So am I,' and someone else said, 'I'm hit as well,'" Bayliss said.

The surveillance video, broadcast on Pakistani television, showed several attackers apparently escaping down a side street on motorcycles while brandishing weapons. Three were shown walking along the middle of the street, apparently in no fear that they were being chased by police.