At least 37 Turkish soldiers have died in Turkey's major incursion inside Syria since it was launched in August to back pro-Ankara Syrian fighters battling IS and Kurdish militia.
Casualties have mounted as the military seeks to take the town of Al-Bab from IS jihadists and Ankara has become more impatient over the lack of support from the US-led coalition against the extremists for the Turkish operation.
"The coalition forces are unfortunately not keeping their promises," Erdogan said at a news conference alongside visiting Guinean President Alpha Conde.
"Whether they do or they don't, we will continue along this path in a determined way. There is no going back on the path we have set out on," he added.
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Turkey has met the fiercest resistance yet of the campaign in the fight for Al-Bab, some 25 kilometres (15 miles) south of the Turkish border.
Erdogan complained that rather than supporting Turkey, the West was backing the Kurdish Peoples' Protection Units (YPG) and Democratic Union Party (PYD), who work with the United States on the ground in Syria, and also IS.
"They are supporting all the terror groups -- the YPG, PYD but also including Daesh (IS)," Erdogan said.
"It's quite clear, perfectly obvious," he said, adding that Turkey could provide proof in pictures and video.
Erdogan had made a similar claim on a visit to Pakistan in November alleging that "the West stands by Daesh right now" and its weapons were Western-made.
But the Turkish leader expressed confidence over the assault saying "we now have the Daesh terror group surrounded on four sides in Al-Bab".
"Yes we have martyrs... but now there's no turning back," he said.
Erdogan made no mention of a video purportedly showing two Turkish soldiers being burned to death by IS in Syria.
Deputy Prime Minister Numan Kurtulmus said earlier there was no information confirming the video.
Erdogan said that along with Russia, Turkey backed a plan to bring the parties in the conflict together with key powers for peace talks in the Kazakh capital Astana.
But he said that "terror groups" must not be included and that Turkey also wanted to see its Gulf allies Saudi Arabia and Qatar involved.
