Britain's Prime Minister Boris Johnson has denied lying to Queen Elizabeth II when advising her to prorogue - or suspend -parliament for a five-week period.

"Absolutely not," Johnson said Thursday, while visiting a London dockyard to announce a new shipbuilding programme.

His comment came after a Scottish court dealt another blow to his Brexit plans Wednesday, ruling that his decision to suspend Parliament less than two months before the UK is due to leave the European Union was an unlawful attempt to avoid democratic scrutiny.

He stressed that the government will appeal the decision, adding that there is still "plenty of time" for lawmakers to debate the departure.

With Brexit due in 50 days, Johnson insists the country must leave the EU on October 31, with or without a divorce deal - but many lawmakers fear a no-deal would be economically devastating.

Johnson on Thursday said the government's assessment there could be food and medicine shortages, gridlock at ports and riots in the streets if there is a no-deal Brexit, was is a worst-case scenario, rather than something that was likely to happen.

He said the bleak scenario detailed in the government's no-deal contingency plan, code-named Operation Yellowhammer, was "not where we intend to end up."

"This is a worst-case scenario which civil servants obviously have to prepare for, but in the last few months, and particularly in the 50 days since I've been prime minister, we've been massively accelerating our preparations," Johnson said.

He insisted a departure deal with the EU was possible by October 31.

UK POOL

London - 12 September 2019

1. UK Prime Minister Boris Johnson onboard ship, as UK announces shipbuilding expansion

2. SOUNDBITE (English) Boris Johnson, UK Prime Minister (commenting on the government's contingency plan in the event of a no-deal Brexit, which was released to the public on Wednesday):

"Well it's very important to understand what this document is. This is a worst case scenario, which civil servants obviously have to prepare for. But in the last few months - and particularly in the 50 days since I've been Prime Minister - we've been massively accelerating our preparations. We're trying to get a deal. I'm very hopeful that we will get a deal with our European friends on October 17 or 18 or thereabouts. But if we have to come out (of the EU) on October 31 with no-deal, we will be ready. And the ports will be ready and the farming communities will be ready and all the industries that matter will be ready for a no-deal Brexit. And what you're looking at here is just the sensible preparations, the worst case scenario, that you'd expect any government to do. In reality, we will certainly be ready for a no-deal Brexit, if we have to do it, - and I stress again that's not where we intend to end up."

3. Wide of Johnson speaking to young sailors

4. SOUNDBITE (English) Boris Johnson, UK Prime Minister:

"I think the British judiciary, the United Kingdom judiciary, is one of the glories of our constitution. They are independent. And believe me, around the world, people look at our judges with awe and admiration. So I'm not going to quarrel or criticise the judges. Clearly, there are two different legal views: the High Court in England had a very different opinion, and the Supreme Court will have to adjudicate in the course of the next few days. And I think it would be proper for politicians to let them get on and do that."

5. Close of Johnson speaking

6. SOUNDBITE (English) Boris Johnson, UK Prime Minister:

Reporter: "Did you lie to the Queen whenyou advised her to prorogue, to suspend, parliament?"

Johnson: "Absolutely not. And indeed, as I say, the High Court in England plainly agrees with us. But the Supreme Court will have to decide. We need a Queen's Speech, we need to get on and do all sorts of things at a national level. We've got a fantastic... here we are, discussing shipbuilding. We're going to be launching five new (Royal Navy) Type-31 frigates. We're going to need bills on education, on health, on housing, on technology, on our vision for investing in science, the space programme, all the things that we want to do on environment, stopping the export of waste overseas and plastics. There are a huge number of things that we want to get on with and do. You can't do them (as things stand right now). We've been going on in this parliament now for longer than any time since the Civil War (in the 1600s). We need a Queen's Speech. We need to to get on with things. And Parliament will have time - both before and after - that crucial (EU) summit on October 17-18 to talk about the Brexit deal. I'm very hopeful that we will get a deal, as I say, at that crucial summit. We're working very hard, I've been around European capitals talking to our friends, I think we can see the rough area of a landing space of how you could do it. It will be tough. It will be hard. But I think we can get there. And the crucial thing is, if we can't get a deal, and I really hope we can, if we can't, then we will be ready to come out on October 31, deal or no-deal, and that's what this is all about."

7. Young sailors