NDP Leader Thomas Mulcair says Prime Minister Stephen Harper should be doing more to help two Canadians who have been jailed in Egypt for more than six weeks without charges.

Mulcair’s comments come one day after it was announced that John Greyson and Dr. Tarek Loubani will be held for an additional 45 days in Cairo’s notorious Tora prison.

Foreign Affairs Minister John Baird said he raised his concerns about the Ontario men’s imprisonment with his Egyptian counterpart late last week.

On Sunday, the Prime Minister’s Office weighed in on the case for the first time since the pair’s arrest, saying in a statement that in the absence of charges against Greyson and Loubani, the two should be released “immediately.”

Mulcair said Monday that while he’s pleased the PMO raised the issue, he’s calling on Harper to do more.

“Now it’s time for action,” he told reporters in Ottawa.

“I think Mr. Baird, in the limits of his mandate, has been able to act appropriately. Now it’s up to the prime minister take it up to another level and that’s what we called upon Prime Minister Harper to do last week.”

Cecilia Greyson, John Greyson’s sister, said she’s grateful for the strongly-worded statement from the PMO, which she said: “Indicates the level of concern that the Canadian government has around this case.”

“Certainly the Ministry of Foreign Affairs has been very active in the case since the beginning and to have the prime minister issue a strong statement really gives us some hope, certainly, that the Canadian government is behind us,” Cecilia told CTV’s Canada AM.

Cecilia said she hopes Harper will be able to talk to Egyptian interim Prime Minister Hazem el-Beblawi, and “hopefully push for a release.”

Greyson and Loubani were arrested on Aug. 16 in Cairo, where they arrived with transit visas on their way to Gaza. The unrest in Egypt prevented them from crossing the border and they were arrested after helping the wounded during one of Cairo’s violent protests.

In a statement released Saturday, the men explained the circumstances surrounding their arrest and described “ridiculous” conditions in the Tora prison. They said they’re sleeping with cockroaches on the concrete floor of a crowded cell and drinking from a “single tap of earthy Nile water.”

In protest, both men began a hunger strike on Sept. 16.

Cecilia said the men’s families and lawyers have provided “ample documentation” to prove that the pair was simply travelling through Egypt in August, but the prosecutor has “shown no interest.”

“We’re really treating this as a human rights issue right now,” she said.

Cecilia Greyson had previously said she believes the Egyptian government has "political motivations" for keeping her brother and Loubani in jail, because the men witnessed numerous deaths during the Aug. 16 protest.