'The previous arrest of Hafiz Muhammed Saeed hasn't made a difference,' a US official said. Hafiz Saeed, a UN-designated terrorist, was arrested on Wednesday. US expresses doubts over Pak's intentions in arresting Hafiz Saeed. Hafiz Saeed is mastermind of 2001 parliament attack, 2008 Mumbai attack

The Trump administration on Friday expressed doubts over Pakistan's intentions in arresting terrorist Hafiz Saeed, the mastermind of the 2001 parliament attack and the 2008 Mumbai attack, saying his previous arrests made no difference either to his activities or that of his terror group Lashkar-e-Taiba.

'We've seen this happen in the past. And we have been looking for sustained and concrete steps, not just window dressing,' a senior administration official told reporters Friday, ahead of Pakistan Prime Minister Imran Khan's visit to the US next week.

Hafiz Saeed, a UN-designated terrorist, was arrested on Wednesday - the seventh time since December 2001, when he was arrested in the immediate aftermath of the terrorist attack on the parliament.

'Let me reassure you, we are clear eyed about the history here. We're under no illusions about the support that we could see from Pakistan's military intelligence services to these groups. So we will look for concrete action,' the official said when asked about the actions that Pakistan has taken against the terrorist group and if the US believes in them.

'I noticed that Pakistan has taken some initial steps such as pledging to seize assets of some of these terrorist groups. And, of course, they put under arrest yesterday Hafiz Muhammed Saeed, the leader of Lashkar-e-Taiba which is responsible for the 2008 Mumbai terrorist attacks,' said the official requesting anonymity.

But the official quickly noted that this was the seventh time that Hafiz Saeed was arrested since the 2001 attack on parliament, when he was detained right after that attack and was subsequently released.

'So we would look to see that Pakistan take sustained action in actually prosecuting these people,' the official said. 'Quite frankly, the previous arrest of Hafiz Muhammed Saeed hasn't made a difference and the LeT has been has been able to operate. So we're monitoring the situation,' said the senior administration official as reporters asked questions on the links between Pakistani intelligence services and terrorist groups.

The US 'remains concerned' about terrorist groups that continue to operate in Pakistan, such as Jaish-e-Mohammed, Lashkar-e-Taiba, and Haqqani network. 'We do have concerns about link between these groups and Pakistan intelligence services in military. That's no secret,' the official said.

The US, the official said, welcomes Prime Minister Khan's pledge that Pakistan will not allow its soil to be used by terror groups and its vocal leadership and the Trump administration is pressing for a new direction in this regard.