The attack in Lahore, where a group of armed gunmen took policemen at a training school hostage, bears resemblance to the Mumbai terror attacks, Pakistan Interior Ministry chief Rehman Malik said on Monday.

"This attack is similar to the Mumbai attacks. We do not know who has done it and cannot be sure until we arrest any culprit and investigate further," Malik said.

"This is not an ordinary attack, it is an attack on Pakistan's integrity," he said.

The Minister said there were intelligence reports on March 15-16, when the lawyers' "Long March' was on, that the country could witness terror attacks and the provincial governments were asked to beef up security.

"There was information on March 15-16. We were told some Uzbeks and terrorists had held a meeting and had decided to dispatch attackers to different parts of the country.

"Provincial governments were thereby informed and asked to take preventive measures," he told Dawn News.

At least 20 policemen, including eight officers, have been killed and 70 others injured when a group of heavily armed terrorists stormed a police training centre near the Wagah border and took several hostages on Monday.

The terrorists believed to be around 14 in number targeted the centre on Monday morning, lobbing grenades and firing indiscriminately, before holing up inside the facility.

On the ongoing attack in Lahore, he said the best possible efforts are being made and top officials are present at the spot to tackle the crisis.

"The Director Generals are present along with paramilitary forces on the spot. Punjab police is the most elite force in the country, we are confident they will tackle it," he said.